Remove spurious pants.pex file that somehow ended up in the repo.
Remove spurious pants.pex file that somehow ended up in the repo.

https://rbcommons.com/s/twitter/r/4214/ introduced this file by accident, unclear how.

Testing Done:
CI passes: https://travis-ci.org/pantsbuild/pants/builds/158908195

Reviewed at https://rbcommons.com/s/twitter/r/4218/

cevaris/pants,kwlzn/pants,pantsbuild/pants,pombredanne/pants,peiyuwang/pants,pombredanne/pants,cevaris/pants,twitter/pants,mateor/pants,pantsbuild/pants,landism/pants,peiyuwang/pants,benjyw/pants,landism/pants,fkorotkov/pants,jsirois/pants,cevaris/pants,lahosken/pants,peiyuwang/pants,15Dkatz/pants,mateor/pants,pantsbuild/pants,lahosken/pants,lahosken/pants,benjyw/pants,tdyas/pants,kwlzn/pants,landism/pants,benjyw/pants,wisechengyi/pants,benjyw/pants,tdyas/pants,mateor/pants,fkorotkov/pants,twitter/pants,fkorotkov/pants,twitter/pants,tdyas/pants,wisechengyi/pants,twitter/pants,baroquebobcat/pants,UnrememberMe/pants,lahosken/pants,pombredanne/pants,ericzundel/pants,twitter/pants,UnrememberMe/pants,wisechengyi/pants,wisechengyi/pants,landism/pants,pombredanne/pants,UnrememberMe/pants,tdyas/pants,cevaris/pants,benjyw/pants,lahosken/pants,wisechengyi/pants,UnrememberMe/pants,fkorotkov/pants,UnrememberMe/pants,ericzundel/pants,UnrememberMe/pants,benjyw/pants,ericzundel/pants,baroquebobcat/pants,wisechengyi/pants,twitter/pants,baroquebobcat/pants,baroquebobcat/pants,twitter/pants,foursquare/pants,15Dkatz/pants,cevaris/pants,landism/pants,tdyas/pants,pantsbuild/pants,mateor/pants,kwlzn/pants,UnrememberMe/pants,twitter/pants,lahosken/pants,kwlzn/pants,foursquare/pants,baroquebobcat/pants,twitter/pants,baroquebobcat/pants,peiyuwang/pants,UnrememberMe/pants,peiyuwang/pants,foursquare/pants,foursquare/pants,kwlzn/pants,kwlzn/pants,wisechengyi/pants,landism/pants,tdyas/pants,ericzundel/pants,wisechengyi/pants,15Dkatz/pants,tdyas/pants,lahosken/pants,mateor/pants,baroquebobcat/pants,cevaris/pants,tdyas/pants,ericzundel/pants,cevaris/pants,baroquebobcat/pants,pantsbuild/pants,pantsbuild/pants,fkorotkov/pants,landism/pants,mateor/pants,15Dkatz/pants,ericzundel/pants,pantsbuild/pants,landism/pants,wisechengyi/pants,jsirois/pants,foursquare/pants,foursquare/pants,lahosken/pants,peiyuwang/pants,benjyw/pants,foursquare/pants,15Dkatz/pants,kwlzn/pants,fkorotkov/pants,foursquare/pants,mateor/pants,pombredanne/pants,mateor/pants,15Dkatz/pants,peiyuwang/pants,15Dkatz/pants,ericzundel/pants,tdyas/pants,foursquare/pants,fkorotkov/pants,UnrememberMe/pants,pombredanne/pants,peiyuwang/pants,ericzundel/pants,pombredanne/pants,jsirois/pants,fkorotkov/pants,15Dkatz/pants,baroquebobcat/pants