Fix fetching for Python 3.9.6 (#24686)

When using Python 3.9.6, Spack is no longer able to fetch anything. Commands like `spack fetch` and `spack install` all break.

Python 3.9.6 includes a [new change](https://github.com/python/cpython/pull/25853/files#diff-b3712475a413ec972134c0260c8f1eb1deefb66184f740ef00c37b4487ef873eR462) that means that `scheme` must be a string, it cannot be None. The solution is to use an empty string like the method default.

Fixes #24644. Also see https://github.com/Homebrew/homebrew-core/pull/80175 where this issue was discovered by CI. Thanks @branchvincent for reporting such a serious issue before any actual users encountered it!

Co-authored-by: Todd Gamblin <tgamblin@llnl.gov>

etc/spack/defaults/cray/modules.yaml

@@ -0,0 +1,21 @@
+# -------------------------------------------------------------------------
+# This is the default configuration for Spack's module file generation.
+#
+# Settings here are versioned with Spack and are intended to provide
+# sensible defaults out of the box. Spack maintainers should edit this
+# file to keep it current.
+#
+# Users can override these settings by editing the following files.
+#
+# Per-spack-instance settings (overrides defaults):
+#   $SPACK_ROOT/etc/spack/modules.yaml
+#
+# Per-user settings (overrides default and site settings):
+#   ~/.spack/modules.yaml
+# -------------------------------------------------------------------------
+modules:
+  prefix_inspections:
+    lib:
+      - LD_LIBRARY_PATH
+    lib64:
+      - LD_LIBRARY_PATH

lib/spack/spack/util/url.py

@@ -11,8 +11,8 @@
 import os.path
 import re
 
-from six import string_types
 import six.moves.urllib.parse as urllib_parse
+from six import string_types
 
 import spack.util.path
 
@@ -151,21 +151,21 @@ def join(base_url, path, *extra, **kwargs):
         for x in itertools.chain((base_url, path), extra)]
     n = len(paths)
     last_abs_component = None
-    scheme = None
+    scheme = ''
     for i in range(n - 1, -1, -1):
         obj = urllib_parse.urlparse(
-            paths[i], scheme=None, allow_fragments=False)
+            paths[i], scheme='', allow_fragments=False)
 
         scheme = obj.scheme
 
         # in either case the component is absolute
-        if scheme is not None or obj.path.startswith('/'):
-            if scheme is None:
+        if scheme or obj.path.startswith('/'):
+            if not scheme:
                 # Without a scheme, we have to go back looking for the
                 # next-last component that specifies a scheme.
                 for j in range(i - 1, -1, -1):
                     obj = urllib_parse.urlparse(
-                        paths[j], scheme=None, allow_fragments=False)
+                        paths[j], scheme='', allow_fragments=False)
 
                     if obj.scheme:
                         paths[i] = '{SM}://{NL}{PATH}'.format(

var/spack/repos/builtin/packages/hdf5/package.py

@@ -167,7 +167,8 @@ def patch(self):
             'fortran/src/H5Fff_F03.f90',
             string=True, ignore_absent=True)
 
-    filter_compiler_wrappers('h5cc', 'h5c++', 'h5fc', relative_root='bin')
+    filter_compiler_wrappers('h5cc', 'h5c++', 'h5fc',
+                             'h5pcc', 'h5pfc', relative_root='bin')
 
     def url_for_version(self, version):
         url = "https://support.hdfgroup.org/ftp/HDF5/releases/hdf5-{0}/hdf5-{1}/src/hdf5-{1}.tar.gz"