py3: make check-py3-compat.py use correct module name at loading pure modules

Before this patch, check-py3-compat.py implies unintentional ".pure"
sub-package name at loading pure modules, because module name is
composed by just replacing "/" in the path to actual ".py" file by
".".

This makes pure modules belong to "mercurial.pure" package, and
prevents them from importing a module belonging to "mercurial" package
relatively by "from . import foo" or so.

This is reason why pure modules fail to import another module
relatively only at examination by check-py3-compat.py.

contrib/check-py3-compat.py

@@ -55,7 +55,7 b' def check_compat_py3(f):'
     # out module paths for things not in a package can be confusing.
     if f.startswith(('hgext/', 'mercurial/')) and not f.endswith('__init__.py'):
         assert f.endswith('.py')
-        name = f.replace('/', '.')[:-3]
+        name = f.replace('/', '.')[:-3].replace('.pure.', '.')
         with open(f, 'r') as fh:
             try:
                 imp.load_module(name, fh, '', ('py', 'r', imp.PY_SOURCE))

tests/test-check-py3-compat.t

@@ -136,9 +136,8 b''
   mercurial/patch.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
   mercurial/pathutil.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
   mercurial/peer.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
-  mercurial/pure/mpatch.py: error importing module: <ImportError> cannot import name 'policy' (line *) (glob)
-  mercurial/pure/osutil.py: error importing module: <ImportError> cannot import name 'policy' (line *) (glob)
-  mercurial/pure/parsers.py: error importing module: <ImportError> No module named 'mercurial.pure.node' (line *) (glob)
+  mercurial/pure/mpatch.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
+  mercurial/pure/parsers.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
   mercurial/pushkey.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
   mercurial/pvec.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
   mercurial/registrar.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)