If I am rebasing a change, and the recipe expectation json files change, I can no longer recipes.py test train. It gives the following error:

Traceback (most recent call last):
  File "/usr/local/google/home/martiniss/src/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/test.py", line 561, in wrapper
    return (True, test, f(test, *args, **kwargs))
  File "/usr/local/google/home/martiniss/src/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/test.py", line 570, in run_worker
    return run_test(test, debug=debug, train=train)
  File "/usr/local/google/home/martiniss/src/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/test.py", line 212, in run_test
    expected = re_encode(json.load(f))
  File "/usr/lib/python2.7/json/__init__.py", line 290, in load
    **kw)
  File "/usr/lib/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 384, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded

I used to be able to do this with simulation_test. This was useful because, if there were merge conflicts in expectation files, I could just retrain, and everything would be fine.