Skip sleep and retry if git remote update exits with a signal
Skip sleep and retry if git remote update exits with a signal

Pressing ctrl-c during repo sync often hangs for 30 to 45 seconds
due to the time.sleep and retry in _RemoteFetch.  If git exits with
a signal, for example -2 for SIGINT triggered by ctrl-c, skip the
sleep and retry.

Change-Id: I32da12c2dcc96d9cc0b12a066e824b12ebfb52a0

jingyu/git-repo,ronan22/repo,flingone/git-repo,nuclearmistake/repo,iAlios/git-repo,petemoore/git-repo,llg84/google_repo,FlymeOS/repo,ediTLJ/git-repo,mozilla/git-repo,slfyusufu/repo,lipro-yocto/git-repo,chzhong/git-repo,xyyangkun/git-repo,qioixiy/git-repo,lewixliu/git-repo,dodocat/git-repo,FuangCao/git-repo,kdavis-mozilla/repo-repo,flingone/git-repo,ediTLJ/git-repo,biaolv/git-repo,kdavis-mozilla/repo-repo,mer-tools/git-repo,kangear/git-repo,CyanogenMod/tools_repo,simbasailor/git-repo,GatorQue/git-repo-flow,biaolv/git-repo,FuangCao/repo,slfyusufu/repo,mixedpuppy/git-repo,gbraad/git-repo,lipro-yocto/git-repo,petemoore/git-repo,xyyangkun/git-repo,simbasailor/git-repo,GatorQue/git-repo-flow,testbetta/repo-pub,aosp-mirror/tools_repo,CyanogenMod/tools_repo,testbetta/git-repo-pub,mozilla/git-repo,qioixiy/git-repo,mixedpuppy/git-repo,GerritCodeReview/git-repo,ronan22/repo,GerritCodeReview/git-repo,wavecomp/git-repo,testbetta/git-repo-pub,FuangCao/git-repo,gbraad/git-repo,aosp-mirror/tools_repo,gabbayo/git-repo,zemug/repo,chenzilin/git-repo,wavecomp/git-repo,FuangCao/repo,lewixliu/git-repo,mer-tools/git-repo,kangear/git-repo,chzhong/git-repo,zemug/repo,qupai/git-repo,couchbasedeps/git-repo,11NJ/git-repo,FlymeOS/repo,4455jkjh/repo,darrengarvey/git-repo,couchbasedeps/git-repo,codetutil/git-repo,gabbayo/git-repo,iAlios/git-repo,frogbywyplay/git-repo,11NJ/git-repo,llg84/google_repo,nuclearmistake/repo,testbetta/repo-pub,chenzilin/git-repo,darrengarvey/git-repo,frogbywyplay/git-repo,TheQtCompany/git-repo,qupai/git-repo,TheQtCompany/git-repo,codetutil/git-repo,jingyu/git-repo,dodocat/git-repo,4455jkjh/repo