diff --git a/lib/spack/spack/test/versions.py b/lib/spack/spack/test/versions.py
index a026403e2e..4624f901c8 100644
--- a/lib/spack/spack/test/versions.py
+++ b/lib/spack/spack/test/versions.py
@@ -43,7 +43,6 @@ def assert_ver_lt(self, a, b):
         self.assertFalse(a > b)
         self.assertFalse(a >= b)
 
-
     def assert_ver_gt(self, a, b):
         a, b = ver(a), ver(b)
         self.assertTrue(a > b)
@@ -53,7 +52,6 @@ def assert_ver_gt(self, a, b):
         self.assertFalse(a < b)
         self.assertFalse(a <= b)
 
-
     def assert_ver_eq(self, a, b):
         a, b = ver(a), ver(b)
         self.assertFalse(a > b)
@@ -63,55 +61,43 @@ def assert_ver_eq(self, a, b):
         self.assertFalse(a < b)
         self.assertTrue(a <= b)
 
-
     def assert_in(self, needle, haystack):
         self.assertTrue(ver(needle) in ver(haystack))
 
-
     def assert_not_in(self, needle, haystack):
         self.assertFalse(ver(needle) in ver(haystack))
 
-
     def assert_canonical(self, canonical_list, version_list):
         self.assertEqual(ver(canonical_list), ver(version_list))
 
-
     def assert_overlaps(self, v1, v2):
         self.assertTrue(ver(v1).overlaps(ver(v2)))
 
-
     def assert_no_overlap(self, v1, v2):
         self.assertFalse(ver(v1).overlaps(ver(v2)))
 
-
     def assert_satisfies(self, v1, v2):
         self.assertTrue(ver(v1).satisfies(ver(v2)))
 
-
     def assert_does_not_satisfy(self, v1, v2):
         self.assertFalse(ver(v1).satisfies(ver(v2)))
 
-
     def check_intersection(self, expected, a, b):
         self.assertEqual(ver(expected), ver(a).intersection(ver(b)))
 
-
     def check_union(self, expected, a, b):
         self.assertEqual(ver(expected), ver(a).union(ver(b)))
 
-
     def test_two_segments(self):
         self.assert_ver_eq('1.0', '1.0')
         self.assert_ver_lt('1.0', '2.0')
         self.assert_ver_gt('2.0', '1.0')
 
-
     def test_three_segments(self):
         self.assert_ver_eq('2.0.1', '2.0.1')
         self.assert_ver_lt('2.0',   '2.0.1')
         self.assert_ver_gt('2.0.1', '2.0')
 
-
     def test_alpha(self):
         # TODO: not sure whether I like this.  2.0.1a is *usually*
         # TODO: less than 2.0.1, but special-casing it makes version
@@ -120,7 +106,6 @@ def test_alpha(self):
         self.assert_ver_gt('2.0.1a', '2.0.1')
         self.assert_ver_lt('2.0.1',  '2.0.1a')
 
-
     def test_patch(self):
         self.assert_ver_eq('5.5p1',  '5.5p1')
         self.assert_ver_lt('5.5p1',  '5.5p2')
@@ -129,7 +114,6 @@ def test_patch(self):
         self.assert_ver_lt('5.5p1',  '5.5p10')
         self.assert_ver_gt('5.5p10', '5.5p1')
 
-
     def test_num_alpha_with_no_separator(self):
         self.assert_ver_lt('10xyz',   '10.1xyz')
         self.assert_ver_gt('10.1xyz', '10xyz')
@@ -137,7 +121,6 @@ def test_num_alpha_with_no_separator(self):
         self.assert_ver_lt('xyz10',   'xyz10.1')
         self.assert_ver_gt('xyz10.1', 'xyz10')
 
-
     def test_alpha_with_dots(self):
         self.assert_ver_eq('xyz.4', 'xyz.4')
         self.assert_ver_lt('xyz.4', '8')
@@ -145,30 +128,25 @@ def test_alpha_with_dots(self):
         self.assert_ver_lt('xyz.4', '2')
         self.assert_ver_gt('2',     'xyz.4')
 
-
     def test_nums_and_patch(self):
         self.assert_ver_lt('5.5p2', '5.6p1')
         self.assert_ver_gt('5.6p1', '5.5p2')
         self.assert_ver_lt('5.6p1', '6.5p1')
         self.assert_ver_gt('6.5p1', '5.6p1')
 
-
     def test_rc_versions(self):
         self.assert_ver_gt('6.0.rc1', '6.0')
         self.assert_ver_lt('6.0',     '6.0.rc1')
 
-
     def test_alpha_beta(self):
         self.assert_ver_gt('10b2', '10a1')
         self.assert_ver_lt('10a2', '10b2')
 
-
     def test_double_alpha(self):
         self.assert_ver_eq('1.0aa', '1.0aa')
         self.assert_ver_lt('1.0a',  '1.0aa')
         self.assert_ver_gt('1.0aa', '1.0a')
 
-
     def test_padded_numbers(self):
         self.assert_ver_eq('10.0001', '10.0001')
         self.assert_ver_eq('10.0001', '10.1')
@@ -176,24 +154,20 @@ def test_padded_numbers(self):
         self.assert_ver_lt('10.0001', '10.0039')
         self.assert_ver_gt('10.0039', '10.0001')
 
-
     def test_close_numbers(self):
         self.assert_ver_lt('4.999.9', '5.0')
         self.assert_ver_gt('5.0',     '4.999.9')
 
-
     def test_date_stamps(self):
         self.assert_ver_eq('20101121', '20101121')
         self.assert_ver_lt('20101121', '20101122')
         self.assert_ver_gt('20101122', '20101121')
 
-
     def test_underscores(self):
         self.assert_ver_eq('2_0', '2_0')
         self.assert_ver_eq('2.0', '2_0')
         self.assert_ver_eq('2_0', '2.0')
 
-
     def test_rpm_oddities(self):
         self.assert_ver_eq('1b.fc17', '1b.fc17')
         self.assert_ver_lt('1b.fc17', '1.fc17')
@@ -202,7 +176,6 @@ def test_rpm_oddities(self):
         self.assert_ver_gt('1g.fc17', '1.fc17')
         self.assert_ver_lt('1.fc17',  '1g.fc17')
 
-
     # Stuff below here is not taken from RPM's tests and is
     # unique to spack
     def test_version_ranges(self):
@@ -214,7 +187,6 @@ def test_version_ranges(self):
         self.assert_ver_lt('1.2:1.4', '1.5:1.6')
         self.assert_ver_gt('1.5:1.6', '1.2:1.4')
 
-
     def test_contains(self):
         self.assert_in('1.3', '1.2:1.4')
         self.assert_in('1.2.5', '1.2:1.4')
@@ -233,7 +205,6 @@ def test_contains(self):
         self.assert_in('1.4.1', '1.2.7:1.4')
         self.assert_not_in('1.4.1', '1.2.7:1.4.0')
 
-
     def test_in_list(self):
         self.assert_in('1.2', ['1.5', '1.2', '1.3'])
         self.assert_in('1.2.5', ['1.5', '1.2:1.3'])
@@ -245,7 +216,6 @@ def test_in_list(self):
         self.assert_not_in('1.2.5:1.5', ['1.5', '1.2:1.3'])
         self.assert_not_in('1.1:1.2.5', ['1.5', '1.2:1.3'])
 
-
     def test_ranges_overlap(self):
         self.assert_overlaps('1.2', '1.2')
         self.assert_overlaps('1.2.1', '1.2.1')
@@ -262,7 +232,6 @@ def test_ranges_overlap(self):
         self.assert_overlaps(':', '1.6:1.9')
         self.assert_overlaps('1.6:1.9', ':')
 
-
     def test_overlap_with_containment(self):
         self.assert_in('1.6.5', '1.6')
         self.assert_in('1.6.5', ':1.6')
@@ -273,7 +242,6 @@ def test_overlap_with_containment(self):
         self.assert_not_in(':1.6', '1.6.5')
         self.assert_in('1.6.5', ':1.6')
 
-
     def test_lists_overlap(self):
         self.assert_overlaps('1.2b:1.7,5', '1.6:1.9,1')
         self.assert_overlaps('1,2,3,4,5', '3,4,5,6,7')
@@ -287,7 +255,6 @@ def test_lists_overlap(self):
         self.assert_no_overlap('1,2,3,4,5', '6,7')
         self.assert_no_overlap('1,2,3,4,5', '6:7')
 
-
     def test_canonicalize_list(self):
         self.assert_canonical(['1.2', '1.3', '1.4'],
                               ['1.2', '1.3', '1.3', '1.4'])
@@ -316,7 +283,6 @@ def test_canonicalize_list(self):
         self.assert_canonical([':'],
                               [':,1.3, 1.3.1,1.3.9,1.4 : 1.5 , 1.3 : 1.4'])
 
-
     def test_intersection(self):
         self.check_intersection('2.5',
                                 '1.0:2.5', '2.5:3.0')
@@ -325,12 +291,11 @@ def test_intersection(self):
         self.check_intersection('0:1', ':', '0:1')
 
         self.check_intersection(['1.0', '2.5:2.7'],
-                                ['1.0:2.7'], ['2.5:3.0','1.0'])
+                                ['1.0:2.7'], ['2.5:3.0', '1.0'])
         self.check_intersection(['2.5:2.7'],
-                                ['1.1:2.7'], ['2.5:3.0','1.0'])
+                                ['1.1:2.7'], ['2.5:3.0', '1.0'])
         self.check_intersection(['0:1'], [':'], ['0:1'])
 
-
     def test_intersect_with_containment(self):
         self.check_intersection('1.6.5', '1.6.5', ':1.6')
         self.check_intersection('1.6.5', ':1.6', '1.6.5')
@@ -338,7 +303,6 @@ def test_intersect_with_containment(self):
         self.check_intersection('1.6:1.6.5', ':1.6.5', '1.6')
         self.check_intersection('1.6:1.6.5', '1.6', ':1.6.5')
 
-
     def test_union_with_containment(self):
         self.check_union(':1.6', '1.6.5', ':1.6')
         self.check_union(':1.6', ':1.6', '1.6.5')
@@ -346,8 +310,6 @@ def test_union_with_containment(self):
         self.check_union(':1.6', ':1.6.5', '1.6')
         self.check_union(':1.6', '1.6', ':1.6.5')
 
-
-    def test_union_with_containment(self):
         self.check_union(':', '1.0:', ':2.0')
 
         self.check_union('1:4', '1:3', '2:4')
@@ -356,7 +318,6 @@ def test_union_with_containment(self):
         # Tests successor/predecessor case.
         self.check_union('1:4', '1:2', '3:4')
 
-
     def test_basic_version_satisfaction(self):
         self.assert_satisfies('4.7.3',   '4.7.3')
 
@@ -372,7 +333,6 @@ def test_basic_version_satisfaction(self):
         self.assert_does_not_satisfy('4.8',   '4.9')
         self.assert_does_not_satisfy('4',     '4.9')
 
-
     def test_basic_version_satisfaction_in_lists(self):
         self.assert_satisfies(['4.7.3'],   ['4.7.3'])
 
@@ -388,7 +348,6 @@ def test_basic_version_satisfaction_in_lists(self):
         self.assert_does_not_satisfy(['4.8'],   ['4.9'])
         self.assert_does_not_satisfy(['4'],     ['4.9'])
 
-
     def test_version_range_satisfaction(self):
         self.assert_satisfies('4.7b6', '4.3:4.7')
         self.assert_satisfies('4.3.0', '4.3:4.7')
@@ -400,7 +359,6 @@ def test_version_range_satisfaction(self):
         self.assert_satisfies('4.7b6',        '4.3:4.7')
         self.assert_does_not_satisfy('4.8.0', '4.3:4.7')
 
-
     def test_version_range_satisfaction_in_lists(self):
         self.assert_satisfies(['4.7b6'], ['4.3:4.7'])
         self.assert_satisfies(['4.3.0'], ['4.3:4.7'])
@@ -423,3 +381,11 @@ def test_satisfaction_with_lists(self):
 
         self.assert_satisfies('4.8.0', '4.2, 4.3:4.8')
         self.assert_satisfies('4.8.2', '4.2, 4.3:4.8')
+
+    def test_formatted_strings(self):
+        versions = '1.2.3', '1_2_3', '1-2-3'
+        for item in versions:
+            v = Version(item)
+            self.assertEqual(v.dotted, '1.2.3')
+            self.assertEqual(v.dashed, '1-2-3')
+            self.assertEqual(v.underscored, '1_2_3')
diff --git a/lib/spack/spack/version.py b/lib/spack/spack/version.py
index 247f6d2362..858d581472 100644
--- a/lib/spack/spack/version.py
+++ b/lib/spack/spack/version.py
@@ -43,16 +43,16 @@
   intersection
   concrete
 """
-import os
-import sys
 import re
 from bisect import bisect_left
 from functools import wraps
+
 from functools_backport import total_ordering
 
 # Valid version characters
 VALID_VERSION = r'[A-Za-z0-9_.-]'
 
+
 def int_if_int(string):
     """Convert a string to int if possible.  Otherwise, return a string."""
     try:
@@ -62,10 +62,11 @@ def int_if_int(string):
 
 
 def coerce_versions(a, b):
-    """Convert both a and b to the 'greatest' type between them, in this order:
+    """
+    Convert both a and b to the 'greatest' type between them, in this order:
            Version < VersionRange < VersionList
-       This is used to simplify comparison operations below so that we're always
-       comparing things that are of the same type.
+    This is used to simplify comparison operations below so that we're always
+    comparing things that are of the same type.
     """
     order = (Version, VersionRange, VersionList)
     ta, tb = type(a), type(b)
@@ -105,6 +106,7 @@ def coercing_method(a, b, *args, **kwargs):
 @total_ordering
 class Version(object):
     """Class to represent versions"""
+
     def __init__(self, string):
         string = str(string)
 
@@ -124,6 +126,17 @@ def __init__(self, string):
         # last element of separators is ''
         self.separators = tuple(re.split(segment_regex, string)[1:-1])
 
+    @property
+    def dotted(self):
+        return '.'.join(str(x) for x in self.version)
+
+    @property
+    def underscored(self):
+        return '_'.join(str(x) for x in self.version)
+
+    @property
+    def dashed(self):
+        return '-'.join(str(x) for x in self.version)
 
     def up_to(self, index):
         """Return a version string up to the specified component, exclusive.
@@ -131,15 +144,12 @@ def up_to(self, index):
         """
         return '.'.join(str(x) for x in self[:index])
 
-
     def lowest(self):
         return self
 
-
     def highest(self):
         return self
 
-
     @coerced
     def satisfies(self, other):
         """A Version 'satisfies' another if it is at least as specific and has a
@@ -147,11 +157,10 @@ def satisfies(self, other):
            gcc@4.7 so that when a user asks to build with gcc@4.7, we can find
            a suitable compiler.
         """
-        nself  = len(self.version)
+        nself = len(self.version)
         nother = len(other.version)
         return nother <= nself and self.version[:nother] == other.version
 
-
     def wildcard(self):
         """Create a regex that will match variants of this version string."""
         def a_or_n(seg):
@@ -181,28 +190,22 @@ def a_or_n(seg):
         wc += '(?:[a-z]|alpha|beta)?)?' * (len(segments) - 1)
         return wc
 
-
     def __iter__(self):
         return iter(self.version)
 
-
     def __getitem__(self, idx):
         return tuple(self.version[idx])
 
-
     def __repr__(self):
         return self.string
 
-
     def __str__(self):
         return self.string
 
-
     @property
     def concrete(self):
         return self
 
-
     @coerced
     def __lt__(self, other):
         """Version comparison is designed for consistency with the way RPM
@@ -235,28 +238,23 @@ def __lt__(self, other):
         # If the common prefix is equal, the one with more segments is bigger.
         return len(self.version) < len(other.version)
 
-
     @coerced
     def __eq__(self, other):
         return (other is not None and
                 type(other) == Version and self.version == other.version)
 
-
     def __ne__(self, other):
         return not (self == other)
 
-
     def __hash__(self):
         return hash(self.version)
 
-
     @coerced
     def __contains__(self, other):
         if other is None:
             return False
         return other.version[:len(self.version)] == self.version
 
-
     def is_predecessor(self, other):
         """True if the other version is the immediate predecessor of this one.
            That is, NO versions v exist such that:
@@ -269,16 +267,13 @@ def is_predecessor(self, other):
         ol = other.version[-1]
         return type(sl) == int and type(ol) == int and (ol - sl == 1)
 
-
     def is_successor(self, other):
         return other.is_predecessor(self)
 
-
     @coerced
     def overlaps(self, other):
         return self in other or other in self
 
-
     @coerced
     def union(self, other):
         if self == other or other in self:
@@ -288,7 +283,6 @@ def union(self, other):
         else:
             return VersionList([self, other])
 
-
     @coerced
     def intersection(self, other):
         if self == other:
@@ -299,6 +293,7 @@ def intersection(self, other):
 
 @total_ordering
 class VersionRange(object):
+
     def __init__(self, start, end):
         if isinstance(start, basestring):
             start = Version(start)
@@ -310,15 +305,12 @@ def __init__(self, start, end):
         if start and end and end < start:
             raise ValueError("Invalid Version range: %s" % self)
 
-
     def lowest(self):
         return self.start
 
-
     def highest(self):
         return self.end
 
-
     @coerced
     def __lt__(self, other):
         """Sort VersionRanges lexicographically so that they are ordered first
@@ -331,28 +323,24 @@ def __lt__(self, other):
 
         s, o = self, other
         if s.start != o.start:
-            return s.start is None or (o.start is not None and s.start < o.start)
+            return s.start is None or (o.start is not None and s.start < o.start)  # NOQA: ignore=E501
 
         return (s.end != o.end and
                 o.end is None or (s.end is not None and s.end < o.end))
 
-
     @coerced
     def __eq__(self, other):
         return (other is not None and
                 type(other) == VersionRange and
                 self.start == other.start and self.end == other.end)
 
-
     def __ne__(self, other):
         return not (self == other)
 
-
     @property
     def concrete(self):
         return self.start if self.start == self.end else None
 
-
     @coerced
     def __contains__(self, other):
         if other is None:
@@ -373,57 +361,55 @@ def __contains__(self, other):
                         other.end in self.end)))
         return in_upper
 
-
     @coerced
     def satisfies(self, other):
-        """A VersionRange satisfies another if some version in this range
-           would satisfy some version in the other range.  To do this it must
-           either:
-             a) Overlap with the other range
-             b) The start of this range satisfies the end of the other range.
+        """
+        A VersionRange satisfies another if some version in this range
+        would satisfy some version in the other range.  To do this it must
+        either:
+          a) Overlap with the other range
+          b) The start of this range satisfies the end of the other range.
 
-           This is essentially the same as overlaps(), but overlaps assumes
-           that its arguments are specific.  That is, 4.7 is interpreted as
-           4.7.0.0.0.0... .  This funciton assumes that 4.7 woudl be satisfied
-           by 4.7.3.5, etc.
+        This is essentially the same as overlaps(), but overlaps assumes
+        that its arguments are specific.  That is, 4.7 is interpreted as
+        4.7.0.0.0.0... .  This funciton assumes that 4.7 woudl be satisfied
+        by 4.7.3.5, etc.
 
-           Rationale:
-           If a user asks for gcc@4.5:4.7, and a package is only compatible with
-           gcc@4.7.3:4.8, then that package should be able to build under the
-           constraints.  Just using overlaps() would not work here.
+        Rationale:
+        If a user asks for gcc@4.5:4.7, and a package is only compatible with
+        gcc@4.7.3:4.8, then that package should be able to build under the
+        constraints.  Just using overlaps() would not work here.
 
-           Note that we don't need to check whether the end of this range
-           would satisfy the start of the other range, because overlaps()
-           already covers that case.
+        Note that we don't need to check whether the end of this range
+        would satisfy the start of the other range, because overlaps()
+        already covers that case.
 
-           Note further that overlaps() is a symmetric operation, while
-           satisfies() is not.
+        Note further that overlaps() is a symmetric operation, while
+        satisfies() is not.
         """
         return (self.overlaps(other) or
                 # if either self.start or other.end are None, then this can't
                 # satisfy, or overlaps() would've taken care of it.
                 self.start and other.end and self.start.satisfies(other.end))
 
-
     @coerced
     def overlaps(self, other):
-        return ((self.start == None or other.end is None or
+        return ((self.start is None or other.end is None or
                  self.start <= other.end or
                  other.end in self.start or self.start in other.end) and
-                (other.start is None or self.end == None or
+                (other.start is None or self.end is None or
                  other.start <= self.end or
                  other.start in self.end or self.end in other.start))
 
-
     @coerced
     def union(self, other):
         if not self.overlaps(other):
             if (self.end is not None and other.start is not None and
-                self.end.is_predecessor(other.start)):
+                    self.end.is_predecessor(other.start)):
                 return VersionRange(self.start, other.end)
 
             if (other.end is not None and self.start is not None and
-                other.end.is_predecessor(self.start)):
+                    other.end.is_predecessor(self.start)):
                 return VersionRange(other.start, self.end)
 
             return VersionList([self, other])
@@ -442,13 +428,12 @@ def union(self, other):
         else:
             end = self.end
             # TODO: See note in intersection() about < and in discrepancy.
-            if not other.end in self.end:
+            if other.end not in self.end:
                 if end in other.end or other.end > self.end:
                     end = other.end
 
         return VersionRange(start, end)
 
-
     @coerced
     def intersection(self, other):
         if self.overlaps(other):
@@ -470,7 +455,7 @@ def intersection(self, other):
                 #     1.6 < 1.6.5  = True  (lexicographic)
                 # Should 1.6 NOT be less than 1.6.5?  Hm.
                 # Here we test (not end in other.end) first to avoid paradox.
-                if other.end is not None and not end in other.end:
+                if other.end is not None and end not in other.end:
                     if other.end < end or other.end in end:
                         end = other.end
 
@@ -479,15 +464,12 @@ def intersection(self, other):
         else:
             return VersionList()
 
-
     def __hash__(self):
         return hash((self.start, self.end))
 
-
     def __repr__(self):
         return self.__str__()
 
-
     def __str__(self):
         out = ""
         if self.start:
@@ -501,6 +483,7 @@ def __str__(self):
 @total_ordering
 class VersionList(object):
     """Sorted, non-redundant list of Versions and VersionRanges."""
+
     def __init__(self, vlist=None):
         self.versions = []
         if vlist is not None:
@@ -515,7 +498,6 @@ def __init__(self, vlist=None):
                 for v in vlist:
                     self.add(ver(v))
 
-
     def add(self, version):
         if type(version) in (Version, VersionRange):
             # This normalizes single-value version ranges.
@@ -524,9 +506,9 @@ def add(self, version):
 
             i = bisect_left(self, version)
 
-            while i-1 >= 0 and version.overlaps(self[i-1]):
-                version = version.union(self[i-1])
-                del self.versions[i-1]
+            while i - 1 >= 0 and version.overlaps(self[i - 1]):
+                version = version.union(self[i - 1])
+                del self.versions[i - 1]
                 i -= 1
 
             while i < len(self) and version.overlaps(self[i]):
@@ -542,7 +524,6 @@ def add(self, version):
         else:
             raise TypeError("Can't add %s to VersionList" % type(version))
 
-
     @property
     def concrete(self):
         if len(self) == 1:
@@ -550,11 +531,9 @@ def concrete(self):
         else:
             return None
 
-
     def copy(self):
         return VersionList(self)
 
-
     def lowest(self):
         """Get the lowest version in the list."""
         if not self:
@@ -562,7 +541,6 @@ def lowest(self):
         else:
             return self[0].lowest()
 
-
     def highest(self):
         """Get the highest version in the list."""
         if not self:
@@ -570,7 +548,6 @@ def highest(self):
         else:
             return self[-1].highest()
 
-
     @coerced
     def overlaps(self, other):
         if not other or not self:
@@ -586,14 +563,12 @@ def overlaps(self, other):
                 o += 1
         return False
 
-
     def to_dict(self):
         """Generate human-readable dict for YAML."""
         if self.concrete:
-            return { 'version'  : str(self[0]) }
+            return {'version': str(self[0])}
         else:
-            return { 'versions' : [str(v) for v in self] }
-
+            return {'versions': [str(v) for v in self]}
 
     @staticmethod
     def from_dict(dictionary):
@@ -605,7 +580,6 @@ def from_dict(dictionary):
         else:
             raise ValueError("Dict must have 'version' or 'versions' in it.")
 
-
     @coerced
     def satisfies(self, other, strict=False):
         """A VersionList satisfies another if some version in the list
@@ -633,20 +607,17 @@ def satisfies(self, other, strict=False):
                 o += 1
         return False
 
-
     @coerced
     def update(self, other):
         for v in other.versions:
             self.add(v)
 
-
     @coerced
     def union(self, other):
         result = self.copy()
         result.update(other)
         return result
 
-
     @coerced
     def intersection(self, other):
         # TODO: make this faster.  This is O(n^2).
@@ -656,7 +627,6 @@ def intersection(self, other):
                 result.add(s.intersection(o))
         return result
 
-
     @coerced
     def intersect(self, other):
         """Intersect this spec's list with other.
@@ -678,50 +648,40 @@ def __contains__(self, other):
             if i == 0:
                 if version not in self[0]:
                     return False
-            elif all(version not in v for v in self[i-1:]):
+            elif all(version not in v for v in self[i - 1:]):
                 return False
 
         return True
 
-
     def __getitem__(self, index):
         return self.versions[index]
 
-
     def __iter__(self):
         return iter(self.versions)
 
-
     def __reversed__(self):
         return reversed(self.versions)
 
-
     def __len__(self):
         return len(self.versions)
 
-
     @coerced
     def __eq__(self, other):
         return other is not None and self.versions == other.versions
 
-
     def __ne__(self, other):
         return not (self == other)
 
-
     @coerced
     def __lt__(self, other):
         return other is not None and self.versions < other.versions
 
-
     def __hash__(self):
         return hash(tuple(self.versions))
 
-
     def __str__(self):
         return ",".join(str(v) for v in self.versions)
 
-
     def __repr__(self):
         return str(self.versions)
 
@@ -730,7 +690,7 @@ def _string_to_version(string):
     """Converts a string to a Version, VersionList, or VersionRange.
        This is private.  Client code should use ver().
     """
-    string = string.replace(' ','')
+    string = string.replace(' ', '')
 
     if ',' in string:
         return VersionList(string.split(','))
@@ -738,7 +698,7 @@ def _string_to_version(string):
     elif ':' in string:
         s, e = string.split(':')
         start = Version(s) if s else None
-        end   = Version(e) if e else None
+        end = Version(e) if e else None
         return VersionRange(start, end)
 
     else:
diff --git a/var/spack/repos/builtin/packages/lmod/package.py b/var/spack/repos/builtin/packages/lmod/package.py
index 0a8b9b4577..7d75866d52 100644
--- a/var/spack/repos/builtin/packages/lmod/package.py
+++ b/var/spack/repos/builtin/packages/lmod/package.py
@@ -23,7 +23,7 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 from spack import *
-import os
+
 
 class Lmod(Package):
     """
@@ -34,17 +34,25 @@ class Lmod(Package):
     variable. Modulefiles for Library packages provide environment variables
     that specify where the library and header files can be found.
     """
-    homepage = "https://www.tacc.utexas.edu/research-development/tacc-projects/lmod"
-    url      = "http://sourceforge.net/projects/lmod/files/Lmod-6.0.1.tar.bz2/download"
+    homepage = 'https://www.tacc.utexas.edu/research-development/tacc-projects/lmod'  # NOQA: ignore=E501
+    url = 'https://github.com/TACC/Lmod/archive/6.4.1.tar.gz'
 
+    version('6.4.1', '7978ba777c8aa41a4d8c05fec5f780f4')
+    version('6.3.7', '0fa4d5a24c41cae03776f781aa2dedc1')
     version('6.0.1', '91abf52fe5033bd419ffe2842ebe7af9')
 
-    depends_on("lua@5.2:")
+    depends_on('lua@5.2:')
+    depends_on('lua-luaposix')
+    depends_on('lua-luafilesystem')
+
+    parallel = False
+
+    def setup_environment(self, spack_env, run_env):
+        stage_lua_path = join_path(
+            self.stage.path, 'Lmod-{version}', 'src', '?.lua')
+        spack_env.append_path('LUA_PATH', stage_lua_path.format(
+            version=self.version), separator=';')
 
     def install(self, spec, prefix):
-        # Add our lua to PATH
-        os.environ['PATH'] = spec['lua'].prefix.bin + ';' + os.environ['PATH']
-        
         configure('--prefix=%s' % prefix)
-        make()
-        make("install")
+        make('install')
diff --git a/var/spack/repos/builtin/packages/lua-luafilesystem/package.py b/var/spack/repos/builtin/packages/lua-luafilesystem/package.py
new file mode 100644
index 0000000000..a61b9dd675
--- /dev/null
+++ b/var/spack/repos/builtin/packages/lua-luafilesystem/package.py
@@ -0,0 +1,51 @@
+##############################################################################
+# Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/llnl/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License (as
+# published by the Free Software Foundation) version 2.1, February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+from spack import *
+
+
+class LuaLuafilesystem(Package):
+    """
+    LuaFileSystem is a Lua library developed to complement the set of
+    functions related to file systems offered by the standard Lua distribution.
+
+    LuaFileSystem offers a portable way to access the underlying directory
+    structure and file attributes.
+
+    LuaFileSystem is free software and uses the same license as Lua 5.1
+    """
+    homepage = 'http://keplerproject.github.io/luafilesystem'
+    url = 'https://github.com/keplerproject/luafilesystem/archive/v_1_6_3.tar.gz'
+
+    version('1_6_3', 'd0552c7e5a082f5bb2865af63fb9dc95')
+
+    extends('lua')
+
+    def install(self, spec, prefix):
+        rockspec_fmt = join_path(self.stage.path,
+                                 'luafilesystem-v_{version.underscored}',
+                                 'rockspecs',
+                                 'luafilesystem-{version.dotted}-1.rockspec')
+        luarocks('--tree=' + prefix, 'install',
+                 rockspec_fmt.format(version=self.spec.version))
diff --git a/var/spack/repos/builtin/packages/lua/package.py b/var/spack/repos/builtin/packages/lua/package.py
index 170f90516a..8ce4a7b94d 100644
--- a/var/spack/repos/builtin/packages/lua/package.py
+++ b/var/spack/repos/builtin/packages/lua/package.py
@@ -57,7 +57,7 @@ class Lua(Package):
         placement='luarocks')
 
     def install(self, spec, prefix):
-        if spec.satisfies("arch=darwin-i686") or spec.satisfies("arch=darwin-x86_64"):
+        if spec.satisfies("arch=darwin-i686") or spec.satisfies("arch=darwin-x86_64"):  # NOQA: ignore=E501
             target = 'macosx'
         else:
             target = 'linux'
@@ -105,6 +105,9 @@ def setup_dependent_environment(self, spack_env, run_env, extension_spec):
         spack_env.set('LUA_PATH', ';'.join(lua_patterns), separator=';')
         spack_env.set('LUA_CPATH', ';'.join(lua_cpatterns), separator=';')
 
+        # Add LUA to PATH for dependent packages
+        spack_env.prepend_path('PATH', self.prefix.bin)
+
         # For run time environment set only the path for extension_spec and
         # prepend it to LUAPATH
         if extension_spec.package.extends(self.spec):
@@ -153,5 +156,5 @@ def setup_dependent_package(self, module, ext_spec):
         """
         # Lua extension builds can have lua and luarocks executable functions
         module.lua = Executable(join_path(self.spec.prefix.bin, 'lua'))
-        module.luarocks = Executable(join_path(self.spec.prefix.bin,
-                                               'luarocks'))
+        module.luarocks = Executable(
+            join_path(self.spec.prefix.bin, 'luarocks'))