Revert "Check for existence of refs upon initial fetch"
Revert "Check for existence of refs upon initial fetch"

This reverts commit 565480588d2bff4205b437862505e77382189811.

We are reverting this change for 2 reasons:

1) It introduced a bug for users using sync -c with a reference mirror.
2) The fetch specs have recently changed to cause git to properly fail
when we request a non-existent branch of a manifest, removing the need
for this change.

Change-Id: I0f63da9bfb40cf5ffafb7979f1b8c929a738fc7b
wavecomp/git-repo,lewixliu/git-repo,aosp-mirror/tools_repo,qupai/git-repo,gbraad/git-repo,darrengarvey/git-repo,TheQtCompany/git-repo,gbraad/git-repo,iAlios/git-repo,dodocat/git-repo,ediTLJ/git-repo,DavidPu/git-repo,kangear/git-repo,xyyangkun/git-repo,FuangCao/repo,mer-tools/git-repo,testbetta/repo-pub,lightsofapollo/git-repo,chzhong/git-repo,TheQtCompany/git-repo,llg84/google_repo,flingone/git-repo,linuxdeepin/git-repo,jingyu/git-repo,petemoore/git-repo,IbpTeam/repo,flingone/git-repo,windyan/git-repo,DavidPu/git-repo,codetutil/git-repo,venus-solar/git-repo,hisilicon/git-repo,iAlios/git-repo,FuangCao/git-repo,gabbayo/git-repo,zemug/repo,chzhong/git-repo,dodocat/git-repo,frogbywyplay/git-repo,lightsofapollo/git-repo,GerritCodeReview/git-repo,xecle/git-repo,petemoore/git-repo,simbasailor/git-repo,wzhy90/git-repo,kangear/git-repo,venus-solar/git-repo,FuangCao/repo,chenzilin/git-repo,hacker-camp/google_repo,slfyusufu/repo,ChronoMonochrome/repo,xecle/git-repo,RuanJG/git-repo,testbetta/git-repo-pub,aosp-mirror/tools_repo,daimajia/git-repo,derron/git-repo,mozilla/git-repo,nuclearmistake/repo,ronan22/repo,mer-tools/git-repo,GatorQue/git-repo-flow,testbetta/git-repo-pub,jingyu/git-repo,mixedpuppy/git-repo,lewixliu/git-repo,hacker-camp/google_repo,couchbasedeps/git-repo,codetutil/git-repo,ronan22/repo,demonyangyue/git-repo,11NJ/git-repo,xyyangkun/git-repo,CyanogenMod/tools_repo,demonyangyue/git-repo,4455jkjh/repo,frogbywyplay/git-repo,daimajia/git-repo,lipro-yocto/git-repo,ediTLJ/git-repo,lipro-yocto/git-repo,GerritCodeReview/git-repo,llg84/google_repo,qioixiy/git-repo,wavecomp/git-repo,qioixiy/git-repo,testbetta/repo-pub,RuanJG/git-repo,IbpTeam/repo,nuclearmistake/repo,couchbasedeps/git-repo,kdavis-mozilla/repo-repo,FlymeOS/repo,slfyusufu/repo,ChronoMonochrome/repo,windyan/git-repo,hisilicon/git-repo,4455jkjh/repo,chenzilin/git-repo,simbasailor/git-repo,gabbayo/git-repo,darrengarvey/git-repo,FlymeOS/repo,11NJ/git-repo,qupai/git-repo,zemug/repo,mozilla/git-repo,kdavis-mozilla/repo-repo,biaolv/git-repo,wzhy90/git-repo,FuangCao/git-repo,CyanogenMod/tools_repo,biaolv/git-repo,derron/git-repo,GatorQue/git-repo-flow,linuxdeepin/git-repo,mixedpuppy/git-repo