Add util.splitpath() and use it instead of using os.sep directly.

This change is intended to allow hooking splitpath() by win32mbcs
extension for MBCS support.

mercurial/util.py

@@ -328,7 +328,7 b' def pathto(root, n1, n2):'
         if os.path.splitdrive(root)[0] != os.path.splitdrive(n1)[0]:
             return os.path.join(root, localpath(n2))
         n2 = '/'.join((pconvert(root), n2))
-    a, b = n1.split(os.sep), n2.split('/')
+    a, b = splitpath(n1), n2.split('/')
     a.reverse()
     b.reverse()
     while a and b and a[-1] == b[-1]:
@@ -692,7 +692,7 b' class path_auditor(object):'
         if path in self.audited:
             return
         normpath = os.path.normcase(path)
-        parts = normpath.split(os.sep)
+        parts = splitpath(normpath)
         if (os.path.splitdrive(path)[0] or parts[0] in ('.hg', '')
             or os.pardir in parts):
             raise Abort(_("path contains illegal component: %s") % path)
@@ -886,6 +886,14 b' def endswithsep(path):'
     '''Check path ends with os.sep or os.altsep.'''
     return path.endswith(os.sep) or os.altsep and path.endswith(os.altsep)
 
+def splitpath(path):
+    '''Split path by os.sep.
+    Note that this function does not use os.altsep because this is
+    an alternative of simple "xxx.split(os.sep)".
+    It is recommended to use os.path.normpath() before using this
+    function if need.'''
+    return path.split(os.sep)
+
 # Platform specific variants
 if os.name == 'nt':
     import msvcrt
@@ -983,7 +991,7 b" if os.name == 'nt':"
         msvcrt.setmode(fd.fileno(), os.O_BINARY)
 
     def pconvert(path):
-        return path.replace("\\", "/")
+        return '/'.join(splitpath(path))
 
     def localpath(path):
         return path.replace('/', '\\')