subrepo: use correct paths for subrepos with ..-relative paths on windows stable

subrepo: use correct paths for subrepos with ..-relative paths on windows

posixpath normpath of c:\foo\bar/../baz is baz, so now we pconvert first.

--- a/mercurial/subrepo.py	Fri Nov 11 01:07:10 2011 +0100
+++ b/mercurial/subrepo.py	Tue Nov 15 02:16:30 2011 +0100
@@ -223,7 +223,7 @@
         source.path = posixpath.normpath(source.path)
         parent = _abssource(repo._subparent, push, abort=False)
         if parent:
-            parent = util.url(parent)
+            parent = util.url(util.pconvert(parent))
             parent.path = posixpath.join(parent.path or '', source.path)
             parent.path = posixpath.normpath(parent.path)
             return str(parent)