Merge branch 'jk/squelch-missing-link-warning-for-unreachable'

Recent "git prune" traverses young unreachable objects to safekeep old objects in the reachability chain from them, which sometimes caused error messages that are unnecessarily alarming. * jk/squelch-missing-link-warning-for-unreachable: suppress errors on missing UNINTERESTING links silence broken link warnings with revs->ignore_missing_links add quieter versions of parse_{tree,commit}