windows: use upper() instead of lower() or os.path.normcase()

this patch uses upper() instead of lower() or os.path.normcase() for
case folding on Windows(NTFS), because lower-ing causes problems for
some languages on it.

see below for detail about problem of lower-ing:

    https://blogs.msdn.com/b/michkap/archive/2005/01/16/353873.aspx

hgext/win32mbcs.py

@@ -127,7 +127,9 b' def wrapname(name, wrapper):'
 # NOTE: os.path.dirname() and os.path.basename() are safe because
 #       they use result of os.path.split()
 funcs = '''os.path.join os.path.split os.path.splitext
- os.path.splitunc os.path.normpath os.path.normcase os.makedirs
+ os.path.splitunc os.path.normpath os.makedirs
+ mercurial.windows.normcase
+ mercurial.util.normcase
  mercurial.util.endswithsep mercurial.util.splitpath mercurial.util.checkcase
  mercurial.util.fspath mercurial.util.pconvert mercurial.util.normpath
  mercurial.util.checkwinfilename mercurial.util.checkosfilename'''

mercurial/windows.py

@@ -131,7 +131,8 b' def localpath(path):'
 def normpath(path):
     return pconvert(os.path.normpath(path))
 
-normcase = os.path.normcase
+def normcase(path):
+    return path.upper()
 
 def realpath(path):
     '''