Use %B format instead of %s\n\n%b to get the raw commit message from a hash.

tests/git_cl_test.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Unit tests for git_cl.py."""
 
 import os
 import StringIO
 import stat
@@ skipping 584 matching lines @@
            description),
           ((['git', 'commit', '--amend', '-m', description],),
            ''),
           ((['git', 'log', '--pretty=format:%s\n\n%b',
              'fake_ancestor_sha..HEAD'],),
            description)
           ]
     if squash:
       ref_to_push = 'abcdef0123456789'
       calls += [
-          ((['git', 'show', '--format=%s\n\n%b', '-s',
+          ((['git', 'show', '--format=%B', '-s',
             'refs/heads/git_cl_uploads/master'],),
            (description, 0)),
           ((['git', 'config', 'branch.master.merge'],),
            'refs/heads/master'),
           ((['git', 'config', 'branch.master.remote'],),
            'origin'),
           ((['get_or_create_merge_base', 'master', 'master'],),
            'origin/master'),
           ((['git', 'rev-parse', 'HEAD:'],),
            '0123456789abcdef'),
@@ skipping 338 matching lines @@
     self.calls += [
       ((['git', 'apply', '--index', '-p0', '--3way'],), '',
        subprocess2.CalledProcessError(1, '', '', '', '')),
     ]
     self.assertNotEqual(git_cl.main(['patch', '123456']), 0)
 
 if __name__ == '__main__':
   git_cl.logging.basicConfig(
       level=git_cl.logging.DEBUG if '-v' in sys.argv else git_cl.logging.ERROR)
   unittest.main()