Don't print "persistent ref" message when syncing quietly
Don't print "persistent ref" message when syncing quietly

The newly introduced "Already have persistent ref" message prevents
repo from overwriting the last line when syncing quietly. Omit the
message when syncing quietly to clean up the output and to restore
the previous behaviour.

Change-Id: Idf42751c67f95924d6de50092ba54d4c6fe93096

codetutil/git-repo,mer-tools/git-repo,lewixliu/git-repo,codetutil/git-repo,aosp-mirror/tools_repo,lipro-yocto/git-repo,lipro-yocto/git-repo,TheQtCompany/git-repo,TheQtCompany/git-repo,lewixliu/git-repo,couchbasedeps/git-repo,gabbayo/git-repo,aosp-mirror/tools_repo,GerritCodeReview/git-repo,couchbasedeps/git-repo,GerritCodeReview/git-repo,mer-tools/git-repo,gabbayo/git-repo