make GM self-test run gm/rebaseline_server unittests

gm/rebaseline_server/test_all.py

 #!/usr/bin/python
 
 """
 Copyright 2014 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 
 Run all unittests within this directory tree, recursing into subdirectories.
 
 TODO(epoger): Launch this automatically on the housekeeper bot, but first make
 sure it works properly after having been checked out (from both git and svn)
 """
 
 import os
 import unittest
 
 
 def main():
   suite = unittest.TestLoader().discover(os.path.dirname(__file__),
                                          pattern='*_test.py')
-  unittest.TextTestRunner(verbosity=2).run(suite)
-
+  results = unittest.TextTestRunner(verbosity=2).run(suite)
+  print repr(results)
+  if not results.wasSuccessful():
+    raise Exception('failed one or more unittests')
 
 if __name__ == '__main__':
   main()