Make sure tests/python/pants_test:all runs all the tests
Make sure tests/python/pants_test:all runs all the tests

tests/python/pants_test:all wasn't running all the tests

Before this change:

% ./pants test tests/python/pants_test:all | grep backend/core/tasks
INFO] Detected git repository at /Users/sbrenn/workspace/pants on branch sbrenn/test-superclass
%

Testing Done:
% ./pants test tests/python/pants_test:all | grep backend/core/tasks
INFO] Detected git repository at /Users/sbrenn/workspace/pants on branch sbrenn/test-all
                     tests/python/pants_test/backend/core/tasks/test_bash_completion.py .
                     tests/python/pants_test/backend/core/tasks/test_dependees.py ..............
                     tests/python/pants_test/backend/core/tasks/test_filter.py ...............
                     tests/python/pants_test/backend/core/tasks/test_markdown_to_html.py ..........
                     tests/python/pants_test/backend/core/tasks/test_mutex_task_mixin.py ....
                     tests/python/pants_test/backend/core/tasks/test_scm_publish.py ........
                     tests/python/pants_test/backend/core/tasks/test_target_filter_task_mixin.py ...
                     tests/python/pants_test/backend/core/tasks/test_test_task_mixin.py ..

 Pull Request: https://github.com/pantsbuild/pants/pull/2322

Reviewed at https://rbcommons.com/s/twitter/r/2932/

ity/pants,cevaris/pants,pantsbuild/pants,jsirois/pants,baroquebobcat/pants,qma/pants,qma/pants,ity/pants,wisechengyi/pants,pantsbuild/pants,landism/pants,tdyas/pants,wisechengyi/pants,ity/pants,cevaris/pants,megaserg/pants,fkorotkov/pants,jtrobec/pants,dturner-tw/pants,slyphon/pants,benjyw/pants,ericzundel/pants,megaserg/pants,15Dkatz/pants,tdyas/pants,jessrosenfield/pants,jtrobec/pants,fkorotkov/pants,wisechengyi/pants,foursquare/pants,manasapte/pants,peiyuwang/pants,pombredanne/pants,twitter/pants,jtrobec/pants,dturner-tw/pants,baroquebobcat/pants,pantsbuild/pants,baroquebobcat/pants,baroquebobcat/pants,jessrosenfield/pants,wisechengyi/pants,twitter/pants,jtrobec/pants,manasapte/pants,tdyas/pants,foursquare/pants,dturner-tw/pants,benjyw/pants,15Dkatz/pants,fkorotkov/pants,pombredanne/pants,wisechengyi/pants,pantsbuild/pants,fkorotkov/pants,gmalmquist/pants,slyphon/pants,landism/pants,qma/pants,UnrememberMe/pants,cevaris/pants,megaserg/pants,dbentley/pants,twitter/pants,pombredanne/pants,wisechengyi/pants,ity/pants,kwlzn/pants,peiyuwang/pants,benjyw/pants,mateor/pants,landism/pants,jessrosenfield/pants,megaserg/pants,tdyas/pants,landism/pants,pantsbuild/pants,pombredanne/pants,lahosken/pants,pombredanne/pants,landism/pants,gmalmquist/pants,jessrosenfield/pants,manasapte/pants,tdyas/pants,jtrobec/pants,UnrememberMe/pants,15Dkatz/pants,ericzundel/pants,15Dkatz/pants,qma/pants,dbentley/pants,ericzundel/pants,jsirois/pants,benjyw/pants,pantsbuild/pants,cevaris/pants,qma/pants,UnrememberMe/pants,benjyw/pants,wisechengyi/pants,fkorotkov/pants,peiyuwang/pants,fkorotkov/pants,manasapte/pants,15Dkatz/pants,foursquare/pants,foursquare/pants,ity/pants,benjyw/pants,pombredanne/pants,peiyuwang/pants,gmalmquist/pants,dturner-tw/pants,twitter/pants,tdyas/pants,slyphon/pants,peiyuwang/pants,dturner-tw/pants,kwlzn/pants,UnrememberMe/pants,jessrosenfield/pants,gmalmquist/pants,mateor/pants,cevaris/pants,baroquebobcat/pants,dbentley/pants,dbentley/pants,UnrememberMe/pants,megaserg/pants,slyphon/pants,kwlzn/pants,kwlzn/pants,gmalmquist/pants,mateor/pants,wisechengyi/pants,foursquare/pants,megaserg/pants,jessrosenfield/pants,baroquebobcat/pants,lahosken/pants,gmalmquist/pants,manasapte/pants,slyphon/pants,dturner-tw/pants,pombredanne/pants,twitter/pants,fkorotkov/pants,manasapte/pants,dbentley/pants,jsirois/pants,dbentley/pants,15Dkatz/pants,tdyas/pants,peiyuwang/pants,kwlzn/pants,baroquebobcat/pants,ity/pants,megaserg/pants,UnrememberMe/pants,benjyw/pants,mateor/pants,kwlzn/pants,mateor/pants,wisechengyi/pants,twitter/pants,lahosken/pants,mateor/pants,manasapte/pants,foursquare/pants,foursquare/pants,landism/pants,ericzundel/pants,pantsbuild/pants,fkorotkov/pants,kwlzn/pants,ity/pants,jtrobec/pants,foursquare/pants,lahosken/pants,baroquebobcat/pants,UnrememberMe/pants,mateor/pants,lahosken/pants,foursquare/pants,peiyuwang/pants,ericzundel/pants,UnrememberMe/pants,dturner-tw/pants,cevaris/pants,gmalmquist/pants,lahosken/pants,twitter/pants,lahosken/pants,qma/pants,lahosken/pants,mateor/pants,15Dkatz/pants,cevaris/pants,landism/pants,twitter/pants,landism/pants,tdyas/pants,ericzundel/pants,qma/pants,ericzundel/pants,dbentley/pants,slyphon/pants,UnrememberMe/pants,twitter/pants,jtrobec/pants,ericzundel/pants,jessrosenfield/pants,slyphon/pants,15Dkatz/pants,baroquebobcat/pants,peiyuwang/pants,tdyas/pants