migrate_config only complain about keys not from defaults
migrate_config only complain about keys not from defaults

has_option seems to return true if a key is found from defaults even if it isn't overridden
in a given section (ours was complaining about 'confs' in a a mostly empty junit-run section).

This seems to fix it, though in the event a section was actually overriding a default,
just with the same value, it will ignore that. I couldn't figure out how to see if a section
actually defined a key without poking around in ConfigParser's private fields.

Reviewed at https://rbcommons.com/s/twitter/r/1451/

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