Merge branch 'pb/log-first-parent-p-m'

Merge branch 'pb/log-first-parent-p-m'

* pb/log-first-parent-p-m:
  show --first-parent/-m: do not default to --cc
  show -c: show patch text
  revision: introduce setup_revision_opt
  t4013: add tests for log -p -m --first-parent
  git log -p -m: document -m and honor --first-parent