Merge branch 'jz/rev-list-exclude-first-parent-only'

"git log" and friends learned an option --exclude-first-parent-only to propagate UNINTERESTING bit down only along the first-parent chain, just like --first-parent option shows commits that lack the UNINTERESTING bit only along the first-parent chain. * jz/rev-list-exclude-first-parent-only: git-rev-list: add --exclude-first-parent-only flag