Fix commit message format returned by getCommitMessage
Fix commit message format returned by getCommitMessage

Git commit messages must have 2 newlines between the subject and body
If used to rewrite a commit message then the commit message will be
incorrectly reformatted.

KieranHayes/arcanist,chundongwang/arcanist,folsom-labs/arcanist,wxstars/arcanist,julkiewicz/arcanist,codelabs-ch/arcanist,coursera/arcanist,calblueprint/arcanist,Khan/arcanist,memsql/arcanist,memsql/arcanist,julkiewicz/arcanist,memsql/arcanist,zhihu/arcanist,folsom-labs/arcanist,r4nt/arcanist,hach-que/arcanist,calblueprint/arcanist,PageUpPeopleOrg/arcanist-patches,codelabs-ch/arcanist,wxstars/arcanist,wharris/arcanist,alexmv/arcanist,haskell-infra/arcanist,jra3/arcanist,Symplicity/arcanist,fivestars/arcanist,fivestars/arcanist,hach-que/arcanist,r4nt/arcanist,Symplicity/arcanist,Khan/arcanist,zhihu/arcanist,fivestars/arcanist,wikimedia/phabricator-arcanist,Symplicity/arcanist,phacility/arcanist,wikimedia/phabricator-arcanist,eSpark/arcanist,wharris/arcanist,coursera/arcanist,PageUpPeopleOrg/arcanist-patches,uber/arcanist,uber/arcanist,chundongwang/arcanist,wharris/arcanist,julkiewicz/arcanist,julkiewicz/arcanist,hach-que/arcanist,Khan/arcanist,codelabs-ch/arcanist,wxstars/arcanist,PageUpPeopleOrg/arcanist-patches,codelabs-ch/arcanist,aik099/arcanist,aik099/arcanist,uber/arcanist,phacility/arcanist,eSpark/arcanist,haskell-infra/arcanist,folsom-labs/arcanist,jra3/arcanist,phacility/arcanist,alexmv/arcanist,aik099/arcanist,haskell-infra/arcanist,codelabs-ch/arcanist,kevinseelbach/arcanist,phacility/arcanist,sneakpeeq/arcanist,wxstars/arcanist,eSpark/arcanist,haskell-infra/arcanist,coursera/arcanist,dguo-coursera/arcanist,calblueprint/arcanist,folsom-labs/arcanist,KieranHayes/arcanist,wharris/arcanist,sneakpeeq/arcanist,KieranHayes/arcanist,Symplicity/arcanist,calblueprint/arcanist,dguo-coursera/arcanist,zhihu/arcanist,hach-que/arcanist,uber/arcanist,fivestars/arcanist,kevinseelbach/arcanist,PageUpPeopleOrg/arcanist-patches,alexmv/arcanist,jra3/arcanist,wikimedia/phabricator-arcanist,zhihu/arcanist,r4nt/arcanist,sneakpeeq/arcanist,eSpark/arcanist,KieranHayes/arcanist,sneakpeeq/arcanist,kevinseelbach/arcanist,jra3/arcanist,kevinseelbach/arcanist,wikimedia/phabricator-arcanist,chundongwang/arcanist,memsql/arcanist,r4nt/arcanist,Khan/arcanist,phacility/arcanist,dguo-coursera/arcanist,chundongwang/arcanist,aik099/arcanist,coursera/arcanist,alexmv/arcanist,dguo-coursera/arcanist