Remove the old setup_py command.
Review Request #1448 - Created Dec. 9, 2014 and submitted
|dturner-tw, ity, jsirois|
It has been replaced by the python_setup goal.
There are no longer any remaining commands in pants, other than GoalRunner.
Note that this requires 49bb9f43eeb1331342f35cef331265cf4b8199bb, so it may not work if you cherry-pick it.