Copy clone-depth in `repo manifest`
Copy clone-depth in `repo manifest`

This argument wasn't being copied, which caused syncs from generated
manifests to pull down too much of the git history.

Change-Id: I269bab788d4557267c081628b3f8c6aec7744e81

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