i18n: use util.pconvert() instead of 'str.replace()' for problematic encoding

some problematic encodings use backslash as part of multi-byte characters.

util.pconvert() can treat strings in such encodings correctly, if
win32mbcs is enabled, but str.replace() can not.

hgext/convert/subversion.py

@@ -197,7 +197,7 b' def issvnurl(ui, url):'
         proto = 'file'
         path = os.path.abspath(url)
     if proto == 'file':
-        path = path.replace(os.sep, '/')
+        path = util.pconvert(path)
     check = protomap.get(proto, lambda *args: False)
     while '/' in path:
         if check(ui, path, proto):