[PATCH v3 0/4] pre-merge-commit hook

This series adds a new pre-merge-commit hook, similar in usage to pre-commit. It also improves hook testing in t7503, by verifying that the correct hooks are run or bypassed as expected.

The original series was done by Michael J Gruber <git@grubix.eu>. I have addressed the outstanding review comments, and noted my changes in the commit messages in "[js: ...]" blocks.

Changes since V2:
* Renamed the hook from "pre-merge" to "pre-merge-commit".
* Added a new patch (1/4) to improve t7503 by verifying that the
  expected hooks are (or are not) run.
* Squashed test changes (from V2's patch 4/4) into patch 3/4.
  Modified the tests to follow the example set in patch 1/4.
* Reworded commit messages to match with the current state of certain
  flags, which changed in between V1 and V2 of this series.

Josh Steadmon (1):
  t7503: verify proper hook execution

Michael J Gruber (3):
  merge: do no-verify like commit
  git-merge: honor pre-merge-commit hook
  merge: --no-verify to bypass pre-merge-commit hook

 Documentation/git-merge.txt                   |   2 +-
 Documentation/githooks.txt                    |   7 +
 Documentation/merge-options.txt               |   4 +
 builtin/merge.c                               |  18 +-
 ...3-pre-commit-and-pre-merge-commit-hooks.sh | 237 ++++++++++++++++++
 t/t7503-pre-commit-hook.sh                    | 139 ----------
 templates/hooks--pre-merge-commit.sample      |  13 +
 7 files changed, 277 insertions(+), 143 deletions(-)
 create mode 100755 t/t7503-pre-commit-and-pre-merge-commit-hooks.sh
 delete mode 100755 t/t7503-pre-commit-hook.sh
 create mode 100755 templates/hooks--pre-merge-commit.sample

Range-diff against v2:
1:  e8b3fd8a5b < -:  ---------- git-merge: Honor pre-merge hook
-:  ---------- > 1:  f0476b2b1e t7503: verify proper hook execution
2:  36406a85be ! 2:  89ddbf410f merge: do no-verify like commit
    @@ Commit message
         "git merge --help" to be more clear that the hook return code is
         respected by default.
     
    -    [js: reworded commit message, and moved documentation changes from patch
    -     3/4 to this commit.]
    +    [js: * reworded commit message
    +         * squashed documentation changes from original series' patch 3/4
    +    ]
     
         Signed-off-by: Michael J Gruber <git@grubix.eu>
    @@ Documentation/git-merge.txt: SYNOPSIS
     +  [--no-verify] [-s <strategy>] [-X <strategy-option>] [-S[<keyid>]]
        [--[no-]allow-unrelated-histories]
        [--[no-]rerere-autoupdate] [-m <msg>] [-F <file>] [<commit>...]
    - 'git merge' --abort
    + 'git merge' (--continue | --abort | --quit)
     
      ## Documentation/merge-options.txt ##
     @@ Documentation/merge-options.txt: option can be used to override --squash.
3:  2440ad35e4 < -:  ---------- merge: --no-verify to bypass pre-merge hook
4:  69dc3696e7 < -:  ---------- t7503: add tests for pre-merge-hook
-:  ---------- > 3:  61b989ff16 git-merge: honor pre-merge-commit hook
-:  ---------- > 4:  45828c56fc merge: --no-verify to bypass pre-merge-commit hook