Merge branch 'jc/reflog-reverse-walk'

An internal function used to implement "git checkout @{-1}" was hard to use correctly. * jc/reflog-reverse-walk: refs.c: fix fread error handling reflog: add for_each_reflog_ent_reverse() API for_each_recent_reflog_ent(): simplify opening of a reflog file for_each_reflog_ent(): extract a helper to process a single entry