Sets checkstyle diff branch to master if no args or branch are set
Sets checkstyle diff branch to master if no args or branch are set

RB_ID=156749
NO-QUEUE=true

(sapling split of 71613a83c5dfcc7b2f405d69a221f3db655e51f5)
brutkin/commons,jsirois/commons,pombredanne/commons,VaybhavSharma/commons,nkhuyu/commons,abel-von/commons,WCCCEDU/twitter-commons,WCCCEDU/twitter-commons,Yasumoto/commons,Yasumoto/commons,jsirois/commons,ericzundel/commons,nkhuyu/commons,Yasumoto/commons,abel-von/commons,jsirois/commons,nkhuyu/commons,atollena/commons,VaybhavSharma/commons,cevaris/commons,cevaris/commons,brutkin/commons,cevaris/commons,atollena/commons,brutkin/commons,ericzundel/commons,atollena/commons,Yasumoto/commons,atollena/commons,ericzundel/commons,ericzundel/commons,abel-von/commons,pombredanne/commons,brutkin/commons,WCCCEDU/twitter-commons,nkhuyu/commons,nkhuyu/commons,jsirois/commons,Yasumoto/commons,pombredanne/commons,pombredanne/commons,atollena/commons,cevaris/commons,VaybhavSharma/commons,VaybhavSharma/commons,abel-von/commons,brutkin/commons,abel-von/commons,WCCCEDU/twitter-commons,ericzundel/commons,pombredanne/commons,WCCCEDU/twitter-commons,jsirois/commons,VaybhavSharma/commons,cevaris/commons