pip install git+https://github.com/RussTedrake/manipulation.git does not install model files

[RussTedrake]

I've confirmed that pip install manipulation (from pypl) does contain the model files. But it seems somehow that the wheel built from the pip direct from git workflow does not.

I suspect it is not using my MANIFEST.in file. But haven't been able to root cause the difference yet.

[RussTedrake]

interestingly, i think it might have been working before 5c879db and/or
the few commits immediately before it.