--- a/mercurial/scmutil.py	Mon Dec 15 13:27:46 2014 -0800
+++ b/mercurial/scmutil.py	Mon Dec 15 13:32:34 2014 -0800
@@ -268,6 +268,12 @@
         to allow handling of strange encoding if needed."""
         return os.path.join(*paths)
 
+    def split(self, path):
+        """split top-most element of a path (as os.path.split would do)
+
+        This exists to allow handling of strange encoding if needed."""
+        return os.path.split(path)
+
     def lexists(self, path=None):
         return os.path.lexists(self.join(path))
 

--- a/mercurial/transaction.py	Mon Dec 15 13:27:46 2014 -0800
+++ b/mercurial/transaction.py	Mon Dec 15 13:32:34 2014 -0800
@@ -12,7 +12,6 @@
 # GNU General Public License version 2 or any later version.
 
 from i18n import _
-import os
 import errno
 import error, util
 
@@ -198,9 +197,9 @@
 
         if file in self.map or file in self._backupmap:
             return
-        dirname, filename = os.path.split(file)
+        vfs = self._vfsmap[location]
+        dirname, filename = vfs.split(file)
         backupfilename = "%s.backup.%s" % (self.journal, filename)
-        vfs = self._vfsmap[location]
         backupfile = vfs.reljoin(dirname, backupfilename)
         if vfs.exists(file):
             filepath = vfs.join(file)