Fix upload.py with git when diff.external is set.

upload.py

 #!/usr/bin/env python
 #
 # Copyright 2007 Google Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
@@ skipping 986 matching lines @@
     super(GitVCS, self).__init__(options)
     # Map of filename -> hash of base file.
     self.base_hashes = {}
 
   def GenerateDiff(self, extra_args):
     # This is more complicated than svn's GenerateDiff because we must convert
     # the diff output to include an svn-style "Index:" line as well as record
     # the hashes of the base files, so we can upload them along with our diff.
     if self.options.revision:
       extra_args = [self.options.revision] + extra_args
-    gitdiff = RunShell(["git", "diff", "--full-index"] + extra_args)
+    gitdiff = RunShell(["git", "diff", "--no-ext-diff", "--full-index"] +
+                       extra_args)
     svndiff = []
     filecount = 0
     filename = None
     for line in gitdiff.splitlines():
       match = re.match(r"diff --git a/(.*) b/.*$", line)
       if match:
         filecount += 1
         filename = match.group(1)
         svndiff.append("Index: %s\n" % filename)
       else:
@@ skipping 353 matching lines @@
   try:
     RealMain(sys.argv)
   except KeyboardInterrupt:
     print
     StatusUpdate("Interrupted.")
     sys.exit(1)
 
 
 if __name__ == "__main__":
   main()