change source archive caching to omit digest from name and instead calculate and compare the checksum. This achieves the original goal of discarding stale cache files without preserving multiple files for the same version.

lib/spack/spack/fetch_strategy.py

@@ -343,7 +343,7 @@ def reset(self):
 
     def __repr__(self):
         url = self.url if self.url else "no url"
-        return "URLFetchStrategy<%s>" % url
+        return "%s<%s>" % (self.__class__.__name__, url)
 
     def __str__(self):
         if self.url:
@@ -352,6 +352,25 @@ def __str__(self):
             return "[no url]"
 
 
+class URLMirrorFetchStrategy(URLFetchStrategy):
+    """The resource associated with a URL at a mirror may be out of date.
+    """
+    def __init__(self, *args, **kwargs):
+        super(URLMirrorFetchStrategy, self).__init__(*args, **kwargs)
+    
+    @_needs_stage
+    def fetch(self):
+        super(URLMirrorFetchStrategy, self).fetch()
+        if self.digest:
+            try:
+                self.check()
+            except ChecksumError:
+                # Future fetchers will assume they don't need to download if the
+                # file remains
+                os.remove(self.archive_file)
+                raise
+
+
 class VCSFetchStrategy(FetchStrategy):
     def __init__(self, name, *rev_types, **kwargs):
         super(VCSFetchStrategy, self).__init__()
@@ -816,7 +835,7 @@ def store(self, copyCmd, relativeDst):
         
     def fetcher(self, targetPath, digest):
         url = "file://" + join_path(self.root, targetPath)
-        return URLFetchStrategy(url, digest)
+        return URLMirrorFetchStrategy(url, digest)
 
 
 class FetchError(spack.error.SpackError):

lib/spack/spack/mirror.py

@@ -61,13 +61,7 @@ def mirror_archive_filename(spec, fetcher):
         # Otherwise we'll make a .tar.gz ourselves
         ext = 'tar.gz'
 
-    tokens = [spec.package.name, spec.version]
-    digests = spec.package.digests
-    if digests:
-        # If a package has multiple digests, any one is sufficient to identify it
-        digestType, digest = sorted(digests.iteritems())[0]
-        tokens.extend([digestType, digest])
-    filename = '-'.join(str(t) for t in tokens)
+    filename = "%s-%s" % (spec.package.name, spec.version)
     if ext:
         filename += ".%s" % ext
     return filename

lib/spack/spack/package.py

@@ -413,15 +413,6 @@ def version(self):
             raise ValueError("Can only get of package with concrete version.")
         return self.spec.versions[0]
 
-    @property
-    def digests(self):
-        """All digests for the concretized package version."""
-        versionInfo = self.versions[self.version]
-        digests = {}
-        if 'md5' in versionInfo:
-            digests['md5'] = versionInfo['md5']
-        return digests 
-
     @memoized
     def version_urls(self):
         """Return a list of URLs for different versions of this