fix string formatting so 'test -h' does not crash
fix string formatting so 'test -h' does not crash

Testing Done:
PANTS_DEV=1 ./pants goal test -h

doesn't crash, unlike

./pants goal test -h

https://travis-ci.org/pantsbuild/pants/builds/41402745

Bugs closed: 805

Reviewed at https://rbcommons.com/s/twitter/r/1353/

fkorotkov/pants,foursquare/pants,wisechengyi/pants,fkorotkov/pants,dgomez10/xanon,mateor/pants,di0spyr0s/pants,jessrosenfield/pants,sameerparekh/pants,di0spyr0s/pants,twitter/pants,laurentgo/pants,sameerparekh/pants,areitz/pants,qma/pants,fkorotkov/pants,TansyArron/pants,dturner-tw/pants,baroquebobcat/pants,sid-kap/pants,pantsbuild/pants,scode/pants,15Dkatz/pants,twitter/pants,kslundberg/pants,pgroudas/pants,jessrosenfield/pants,kslundberg/pants,laurentgo/pants,pombredanne/pants,dbentley/pants,slyphon/pants,jessrosenfield/pants,sid-kap/pants,jtrobec/pants,kwlzn/pants,cevaris/pants,wisechengyi/pants,pombredanne/pants,wisechengyi/pants,pgroudas/pants,pgroudas/pants,mateor/pants,TansyArron/pants,dgomez10/xanon,15Dkatz/pants,lahosken/pants,di0spyr0s/pants,foursquare/pants,cevaris/pants,megaserg/pants,slyphon/pants,ity/pants,baroquebobcat/pants,megaserg/pants,Gabriel439/pants,lahosken/pants,landism/pants,ericzundel/pants,dgomez10/xanon,tejal29/pants,baroquebobcat/pants,fkorotkov/pants,peiyuwang/pants,areitz/pants,dgomez10/xanon,kwlzn/pants,benjyw/pants,dgomez10/xanon,ity/pants,kwlzn/pants,kwlzn/pants,TansyArron/pants,manasapte/pants,baroquebobcat/pants,manasapte/pants,Gabriel439/pants,foursquare/pants,ericzundel/pants,dgomez10/xanon,mateor/pants,areitz/pants,dbentley/pants,UnrememberMe/pants,sid-kap/pants,kwlzn/pants,sameerparekh/pants,kwlzn/pants,dturner-tw/pants,digwanderlust/pants,laurentgo/pants,peiyuwang/pants,jtrobec/pants,wisechengyi/pants,kslundberg/pants,tdyas/pants,megaserg/pants,jessrosenfield/pants,15Dkatz/pants,foursquare/pants,UnrememberMe/pants,digwanderlust/pants,manasapte/pants,mateor/pants,TansyArron/pants,qma/pants,laurentgo/pants,laurentgo/pants,twitter/pants,wisechengyi/pants,scode/pants,pantsbuild/pants,jtrobec/pants,Gabriel439/pants,15Dkatz/pants,twitter/pants,15Dkatz/pants,areitz/pants,ity/pants,areitz/pants,qma/pants,peiyuwang/pants,peiyuwang/pants,UnrememberMe/pants,dturner-tw/pants,tdyas/pants,di0spyr0s/pants,tdyas/pants,di0spyr0s/pants,baroquebobcat/pants,foursquare/pants,twitter/pants,ericzundel/pants,qma/pants,kslundberg/pants,dgomez10/xanon,peiyuwang/pants,benjyw/pants,areitz/pants,pantsbuild/pants,pgroudas/pants,lahosken/pants,megaserg/pants,pombredanne/pants,pgroudas/pants,gmalmquist/pants,jtrobec/pants,scode/pants,di0spyr0s/pants,baroquebobcat/pants,tejal29/pants,foursquare/pants,gmalmquist/pants,peiyuwang/pants,TansyArron/pants,fkorotkov/pants,ericzundel/pants,twitter/pants,UnrememberMe/pants,fkorotkov/pants,lahosken/pants,ity/pants,15Dkatz/pants,pombredanne/pants,twitter/pants,dbentley/pants,dgomez10/xanon,dturner-tw/pants,TansyArron/pants,digwanderlust/pants,jtrobec/pants,landism/pants,slyphon/pants,slyphon/pants,square/pants,dbentley/pants,pombredanne/pants,sameerparekh/pants,tejal29/pants,dbentley/pants,ity/pants,jsirois/pants,jessrosenfield/pants,pantsbuild/pants,landism/pants,mateor/pants,megaserg/pants,ericzundel/pants,digwanderlust/pants,scode/pants,tdyas/pants,TansyArron/pants,qma/pants,mateor/pants,UnrememberMe/pants,sid-kap/pants,lahosken/pants,landism/pants,wisechengyi/pants,ericzundel/pants,cevaris/pants,pombredanne/pants,cevaris/pants,foursquare/pants,sid-kap/pants,sid-kap/pants,mateor/pants,peiyuwang/pants,pgroudas/pants,digwanderlust/pants,wisechengyi/pants,tejal29/pants,pantsbuild/pants,gmalmquist/pants,ericzundel/pants,dbentley/pants,di0spyr0s/pants,sameerparekh/pants,UnrememberMe/pants,dgomez10/xanon,slyphon/pants,tdyas/pants,gmalmquist/pants,tdyas/pants,tdyas/pants,baroquebobcat/pants,dturner-tw/pants,landism/pants,benjyw/pants,baroquebobcat/pants,cevaris/pants,Gabriel439/pants,cevaris/pants,slyphon/pants,foursquare/pants,gmalmquist/pants,dturner-tw/pants,gmalmquist/pants,dbentley/pants,manasapte/pants,jsirois/pants,manasapte/pants,foursquare/pants,twitter/pants,Gabriel439/pants,lahosken/pants,mateor/pants,dturner-tw/pants,jtrobec/pants,wisechengyi/pants,sameerparekh/pants,Gabriel439/pants,scode/pants,landism/pants,manasapte/pants,dgomez10/xanon,gmalmquist/pants,scode/pants,pombredanne/pants,square/pants,15Dkatz/pants,ity/pants,UnrememberMe/pants,wisechengyi/pants,jessrosenfield/pants,tdyas/pants,pantsbuild/pants,sameerparekh/pants,pantsbuild/pants,ity/pants,benjyw/pants,landism/pants,square/pants,tejal29/pants,dgomez10/xanon,sid-kap/pants,qma/pants,kwlzn/pants,slyphon/pants,UnrememberMe/pants,areitz/pants,kslundberg/pants,lahosken/pants,jtrobec/pants,benjyw/pants,jsirois/pants,fkorotkov/pants,benjyw/pants,kslundberg/pants,UnrememberMe/pants,ericzundel/pants,peiyuwang/pants,laurentgo/pants,qma/pants,jessrosenfield/pants,manasapte/pants,megaserg/pants,digwanderlust/pants,scode/pants,baroquebobcat/pants,cevaris/pants,square/pants,15Dkatz/pants,kslundberg/pants,twitter/pants,megaserg/pants,tdyas/pants,Gabriel439/pants,benjyw/pants,lahosken/pants,fkorotkov/pants,landism/pants