Drop Python 3.6 again (#34442)

lib/spack/spack/binary_distribution.py

@@ -1050,7 +1050,7 @@ def generate_package_index(cache_prefix, concurrency=32):
     try:
         file_list, read_fn = _spec_files_from_cache(cache_prefix)
     except ListMirrorSpecsError as err:
-        tty.error("Unabled to generate package index, {0}".format(err))
+        tty.error("Unable to generate package index, {0}".format(err))
         return
 
     tty.debug("Retrieving spec descriptor files from {0} to build index".format(cache_prefix))

var/spack/repos/builtin/packages/py-dataclasses/package.py

@@ -15,5 +15,9 @@ class PyDataclasses(PythonPackage):
     version("0.8", sha256="8479067f342acf957dc82ec415d355ab5edb7e7646b90dc6e2fd1d96ad084c97")
     version("0.7", sha256="494a6dcae3b8bcf80848eea2ef64c0cc5cd307ffc263e17cdf42f3e5420808e6")
 
-    depends_on("python@3.6.00:3.6", type=("build", "run"))
     depends_on("py-setuptools", type="build")
+
+    # Python 3.6 is not supported for installation, but need to support bootstrapping,
+    # so comment out the following line.
+    # depends_on("python@3.6", type=("build", "run"))
+    conflicts("^python@:3.5,3.7:")

var/spack/repos/builtin/packages/python/package.py

@@ -107,13 +107,6 @@ class Python(Package):
     version("3.7.1", sha256="36c1b81ac29d0f8341f727ef40864d99d8206897be96be73dc34d4739c9c9f06")
     version("3.7.0", sha256="85bb9feb6863e04fb1700b018d9d42d1caac178559ffa453d7e6a436e259fd0d")
 
-    # Python 3.6.15 has been added back only to allow bootstrapping Spack on Python 3.6
-    version(
-        "3.6.15",
-        sha256="54570b7e339e2cfd72b29c7e2fdb47c0b7b18b7412e61de5b463fc087c13b043",
-        deprecated=True,
-    )
-
     extendable = True
 
     # Variants to avoid cyclical dependencies for concretizer