windows: use normalized path to check repository nesting

current "localrepository._checknested()" uses specified path itself to
compare against subrepo pathes.

it is invoked from "hgsubrepo.subrepo()" or pathauditor (as callback),
and both use "os.sep" as separator.

this causes unexpected nesting check result, if subrepo configuration
uses "/" as path separator for sub repo path.

this path uses "/" to join path components (or apply "util.pconvert()"
on path) to normalize.

mercurial/localrepo.py

@@ -127,6 +127,7 b' class localrepository(repo.repository):'
         if not path.startswith(self.root):
             return False
         subpath = path[len(self.root) + 1:]
+        normsubpath = util.pconvert(subpath)
 
         # XXX: Checking against the current working copy is wrong in
         # the sense that it can reject things like
@@ -148,9 +149,9 b' class localrepository(repo.repository):'
         ctx = self[None]
         parts = util.splitpath(subpath)
         while parts:
-            prefix = os.sep.join(parts)
+            prefix = '/'.join(parts)
             if prefix in ctx.substate:
-                if prefix == subpath:
+                if prefix == normsubpath:
                     return True
                 else:
                     sub = ctx.sub(prefix)