Merge branch 'ab/racy-hooks'

Code clean-up to allow callers of run_commit_hook() to learn if it
got "success" because the hook succeeded or because there wasn't
any hook.

* ab/racy-hooks:
  hooks: fix an obscure TOCTOU "did we just run a hook?" race
  merge: don't run post-hook logic on --no-verify

diff --cc builtin/receive-pack.c
Simple merge

diff --cc commit.c
Simple merge