[JENKINS-46041] If guessBrowser fails, return null and move on.
[JENKINS-46041] If guessBrowser fails, return null and move on.

stephenc/jenkins,MarkEWaite/jenkins,ikedam/jenkins,batmat/jenkins,daniel-beck/jenkins,oleg-nenashev/jenkins,stephenc/jenkins,damianszczepanik/jenkins,amuniz/jenkins,DanielWeber/jenkins,ikedam/jenkins,Jochen-A-Fuerbacher/jenkins,DanielWeber/jenkins,recena/jenkins,MarkEWaite/jenkins,andresrc/jenkins,daniel-beck/jenkins,pjanouse/jenkins,andresrc/jenkins,ErikVerheul/jenkins,ikedam/jenkins,godfath3r/jenkins,v1v/jenkins,batmat/jenkins,godfath3r/jenkins,patbos/jenkins,rsandell/jenkins,Jochen-A-Fuerbacher/jenkins,viqueen/jenkins,recena/jenkins,oleg-nenashev/jenkins,ikedam/jenkins,damianszczepanik/jenkins,aldaris/jenkins,v1v/jenkins,sathiya-mit/jenkins,patbos/jenkins,batmat/jenkins,stephenc/jenkins,ErikVerheul/jenkins,kohsuke/hudson,damianszczepanik/jenkins,dariver/jenkins,kohsuke/hudson,batmat/jenkins,MarkEWaite/jenkins,MarkEWaite/jenkins,godfath3r/jenkins,ErikVerheul/jenkins,sathiya-mit/jenkins,v1v/jenkins,amuniz/jenkins,MarkEWaite/jenkins,Vlatombe/jenkins,ErikVerheul/jenkins,ikedam/jenkins,Jochen-A-Fuerbacher/jenkins,pjanouse/jenkins,rsandell/jenkins,bkmeneguello/jenkins,daniel-beck/jenkins,Jochen-A-Fuerbacher/jenkins,rsandell/jenkins,ErikVerheul/jenkins,v1v/jenkins,kohsuke/hudson,godfath3r/jenkins,aldaris/jenkins,DanielWeber/jenkins,kohsuke/hudson,amuniz/jenkins,batmat/jenkins,recena/jenkins,Vlatombe/jenkins,daniel-beck/jenkins,viqueen/jenkins,pjanouse/jenkins,amuniz/jenkins,dariver/jenkins,pjanouse/jenkins,daniel-beck/jenkins,stephenc/jenkins,v1v/jenkins,viqueen/jenkins,recena/jenkins,DanielWeber/jenkins,kohsuke/hudson,andresrc/jenkins,Jochen-A-Fuerbacher/jenkins,viqueen/jenkins,batmat/jenkins,Jochen-A-Fuerbacher/jenkins,DanielWeber/jenkins,godfath3r/jenkins,jenkinsci/jenkins,bkmeneguello/jenkins,sathiya-mit/jenkins,sathiya-mit/jenkins,ikedam/jenkins,rsandell/jenkins,oleg-nenashev/jenkins,MarkEWaite/jenkins,Jochen-A-Fuerbacher/jenkins,jenkinsci/jenkins,kohsuke/hudson,sathiya-mit/jenkins,damianszczepanik/jenkins,damianszczepanik/jenkins,Vlatombe/jenkins,ErikVerheul/jenkins,bkmeneguello/jenkins,stephenc/jenkins,sathiya-mit/jenkins,jenkinsci/jenkins,ikedam/jenkins,patbos/jenkins,oleg-nenashev/jenkins,dariver/jenkins,damianszczepanik/jenkins,andresrc/jenkins,aldaris/jenkins,andresrc/jenkins,daniel-beck/jenkins,kohsuke/hudson,amuniz/jenkins,sathiya-mit/jenkins,andresrc/jenkins,damianszczepanik/jenkins,Vlatombe/jenkins,andresrc/jenkins,dariver/jenkins,dariver/jenkins,recena/jenkins,rsandell/jenkins,viqueen/jenkins,pjanouse/jenkins,kohsuke/hudson,Vlatombe/jenkins,rsandell/jenkins,jenkinsci/jenkins,patbos/jenkins,DanielWeber/jenkins,batmat/jenkins,jenkinsci/jenkins,patbos/jenkins,ErikVerheul/jenkins,rsandell/jenkins,godfath3r/jenkins,bkmeneguello/jenkins,amuniz/jenkins,recena/jenkins,viqueen/jenkins,bkmeneguello/jenkins,DanielWeber/jenkins,oleg-nenashev/jenkins,Vlatombe/jenkins,pjanouse/jenkins,daniel-beck/jenkins,oleg-nenashev/jenkins,bkmeneguello/jenkins,bkmeneguello/jenkins,aldaris/jenkins,pjanouse/jenkins,stephenc/jenkins,godfath3r/jenkins,aldaris/jenkins,oleg-nenashev/jenkins,recena/jenkins,v1v/jenkins,Vlatombe/jenkins,aldaris/jenkins,jenkinsci/jenkins,aldaris/jenkins,ikedam/jenkins,dariver/jenkins,viqueen/jenkins,damianszczepanik/jenkins,amuniz/jenkins,jenkinsci/jenkins,MarkEWaite/jenkins,patbos/jenkins,daniel-beck/jenkins,stephenc/jenkins,jenkinsci/jenkins,dariver/jenkins,rsandell/jenkins,v1v/jenkins,MarkEWaite/jenkins,patbos/jenkins