Update CheckoutBranch to the wptrunner changes.
Update CheckoutBranch to the wptrunner changes.

This is a port of <https://hg.mozilla.org/mozilla-central/rev/c0b8fea5aef4>.

SimonSapin/servo,ConnorGBrewster/servo,anthgur/servo,fiji-flo/servo,splav/servo,mbrubeck/servo,nnethercote/servo,notriddle/servo,thiagopnts/servo,notriddle/servo,peterjoel/servo,emilio/servo,CJ8664/servo,eddyb/servo,ConnorGBrewster/servo,AnthonyBroadCrawford/servo,upsuper/servo,nnethercote/servo,emilio/servo,emilio/servo,AnthonyBroadCrawford/servo,KiChjang/servo,CJ8664/servo,saneyuki/servo,pyfisch/servo,jimberlage/servo,paulrouget/servo,avadacatavra/servo,szeged/servo,paulrouget/servo,jimberlage/servo,canaltinova/servo,CJ8664/servo,thiagopnts/servo,notriddle/servo,fiji-flo/servo,notriddle/servo,dsandeephegde/servo,bjwbell/servo,j3parker/servo,DominoTree/servo,nrc/servo,ConnorGBrewster/servo,bjwbell/servo,dati91/servo,larsbergstrom/servo,brendandahl/servo,larsbergstrom/servo,brendandahl/servo,bjwbell/servo,runarberg/servo,nrc/servo,szeged/servo,paulrouget/servo,canaltinova/servo,eddyb/servo,paulrouget/servo,runarberg/servo,AnthonyBroadCrawford/servo,jimberlage/servo,nnethercote/servo,bjwbell/servo,upsuper/servo,dagnir/servo,AnthonyBroadCrawford/servo,saneyuki/servo,nnethercote/servo,CJ8664/servo,steveklabnik/servo,rnestler/servo,thiagopnts/servo,dati91/servo,thiagopnts/servo,szeged/servo,saneyuki/servo,larsbergstrom/servo,sadmansk/servo,splav/servo,nnethercote/servo,splav/servo,DominoTree/servo,dagnir/servo,peterjoel/servo,splav/servo,DominoTree/servo,fiji-flo/servo,runarberg/servo,runarberg/servo,eddyb/servo,mbrubeck/servo,SimonSapin/servo,thiagopnts/servo,eddyb/servo,sadmansk/servo,mattnenterprise/servo,paulrouget/servo,DominoTree/servo,ConnorGBrewster/servo,jimberlage/servo,brendandahl/servo,rnestler/servo,SimonSapin/servo,dagnir/servo,RenaudParis/servo,splav/servo,mbrubeck/servo,larsbergstrom/servo,emilio/servo,steveklabnik/servo,emilio/servo,pyfisch/servo,rnestler/servo,jimberlage/servo,notriddle/servo,dati91/servo,KiChjang/servo,notriddle/servo,dsandeephegde/servo,pyfisch/servo,dati91/servo,RenaudParis/servo,RenaudParis/servo,paulrouget/servo,pyfisch/servo,canaltinova/servo,szeged/servo,saneyuki/servo,paulrouget/servo,brendandahl/servo,KiChjang/servo,canaltinova/servo,avadacatavra/servo,cbrewster/servo,larsbergstrom/servo,thiagopnts/servo,anthgur/servo,dsandeephegde/servo,bjwbell/servo,KiChjang/servo,peterjoel/servo,saneyuki/servo,szeged/servo,runarberg/servo,larsbergstrom/servo,runarberg/servo,sadmansk/servo,steveklabnik/servo,SimonSapin/servo,sadmansk/servo,rnestler/servo,mbrubeck/servo,pyfisch/servo,avadacatavra/servo,DominoTree/servo,anthgur/servo,AnthonyBroadCrawford/servo,brendandahl/servo,mattnenterprise/servo,nrc/servo,saneyuki/servo,dsandeephegde/servo,anthgur/servo,anthgur/servo,saneyuki/servo,emilio/servo,emilio/servo,mattnenterprise/servo,canaltinova/servo,rnestler/servo,j3parker/servo,mbrubeck/servo,sadmansk/servo,runarberg/servo,AnthonyBroadCrawford/servo,larsbergstrom/servo,CJ8664/servo,dsandeephegde/servo,nrc/servo,dagnir/servo,dsandeephegde/servo,j3parker/servo,cbrewster/servo,AnthonyBroadCrawford/servo,RenaudParis/servo,eddyb/servo,eddyb/servo,peterjoel/servo,cbrewster/servo,steveklabnik/servo,ConnorGBrewster/servo,thiagopnts/servo,peterjoel/servo,SimonSapin/servo,rnestler/servo,upsuper/servo,dsandeephegde/servo,sadmansk/servo,mbrubeck/servo,upsuper/servo,nnethercote/servo,notriddle/servo,DominoTree/servo,SimonSapin/servo,peterjoel/servo,dati91/servo,notriddle/servo,notriddle/servo,j3parker/servo,avadacatavra/servo,splav/servo,eddyb/servo,jimberlage/servo,szeged/servo,fiji-flo/servo,paulrouget/servo,notriddle/servo,fiji-flo/servo,emilio/servo,szeged/servo,paulrouget/servo,pyfisch/servo,szeged/servo,szeged/servo,fiji-flo/servo,rnestler/servo,szeged/servo,mbrubeck/servo,avadacatavra/servo,paulrouget/servo,canaltinova/servo,KiChjang/servo,pyfisch/servo,peterjoel/servo,rnestler/servo,saneyuki/servo,mbrubeck/servo,larsbergstrom/servo,dagnir/servo,anthgur/servo,ConnorGBrewster/servo,cbrewster/servo,upsuper/servo,dati91/servo,larsbergstrom/servo,j3parker/servo,dati91/servo,emilio/servo,jimberlage/servo,SimonSapin/servo,canaltinova/servo,j3parker/servo,canaltinova/servo,dati91/servo,KiChjang/servo,KiChjang/servo,fiji-flo/servo,peterjoel/servo,dagnir/servo,dsandeephegde/servo,ConnorGBrewster/servo,saneyuki/servo,jimberlage/servo,j3parker/servo,sadmansk/servo,cbrewster/servo,nrc/servo,mattnenterprise/servo,mattnenterprise/servo,larsbergstrom/servo,DominoTree/servo,mattnenterprise/servo,KiChjang/servo,peterjoel/servo,anthgur/servo,sadmansk/servo,RenaudParis/servo,CJ8664/servo,pyfisch/servo,ConnorGBrewster/servo,nrc/servo,splav/servo,bjwbell/servo,emilio/servo,DominoTree/servo,steveklabnik/servo,thiagopnts/servo,avadacatavra/servo,upsuper/servo,CJ8664/servo,brendandahl/servo,splav/servo,brendandahl/servo,splav/servo,saneyuki/servo,eddyb/servo,upsuper/servo,pyfisch/servo,pyfisch/servo,nnethercote/servo,avadacatavra/servo,nrc/servo,dagnir/servo,RenaudParis/servo,RenaudParis/servo,mattnenterprise/servo,mattnenterprise/servo,splav/servo,cbrewster/servo,DominoTree/servo,upsuper/servo,cbrewster/servo,SimonSapin/servo,KiChjang/servo,steveklabnik/servo,avadacatavra/servo,steveklabnik/servo,jimberlage/servo,DominoTree/servo,nnethercote/servo,CJ8664/servo,anthgur/servo,peterjoel/servo,nnethercote/servo,nnethercote/servo,bjwbell/servo,cbrewster/servo,fiji-flo/servo,KiChjang/servo