[PATCH 0/3] Do not be totally silent upon lock error

[Junio C Hamano <gitster@pobox.com>]

Robbie Iannucci reported that "git merge" that fast-forwards fails
silently when a competing or stale index.lock is present in recent
Git:

    $ git merge --ff-only master; echo $?
    Updating 454cb6bd52..8d7a455ed5
    1
    $ exit

Did the update happen?  We used to give "fatal: Unable to create
..." followed by "Another git process seems to be running..."
advice, and that would have helped the user from the confusion.

This was because there were only two choices available to the
callers of the lockfile API--they can either ask it to die with
message when the lock cannot be acquired, or ask it to silently
return -1 to signal an error. The recent "libify sequencer" topic
turned many existing "please die" calls to "just silently return
-1", and while it added new "unable to lock" error messages to most
of them, one spot didn't get any and now is allowed to just die
silently.

This series should fix it:

 - 1/3 is something I noticed while reading the existing callers of
   the lockfile API, and is not a new issue with "libify sequencer"
   topic.

 - 2/3 gives a new third option to callers of the lockfile API; they
   can now say "please emit the usual error message upon failing to
   acquire the lock, but give control back to me".

 - 3/3 uses the new option to resurrect the message.

Junio C Hamano (3):
  wt-status: implement opportunisitc index update correctly
  hold_locked_index(): align error handling with hold_lockfile_for_update()
  lockfile: LOCK_REPORT_ON_ERROR

 apply.c                          |  2 +-
 builtin/add.c                    |  2 +-
 builtin/am.c                     |  6 +++---
 builtin/checkout-index.c         |  2 +-
 builtin/checkout.c               |  4 ++--
 builtin/clone.c                  |  2 +-
 builtin/commit.c                 |  8 ++++----
 builtin/merge.c                  |  6 +++---
 builtin/mv.c                     |  2 +-
 builtin/read-tree.c              |  2 +-
 builtin/reset.c                  |  2 +-
 builtin/rm.c                     |  2 +-
 builtin/update-index.c           |  1 +
 lockfile.c                       | 12 ++++++++++--
 lockfile.h                       |  8 +++++++-
 merge-recursive.c                |  2 +-
 merge.c                          |  2 +-
 read-cache.c                     |  7 ++-----
 rerere.c                         |  2 +-
 sequencer.c                      |  2 +-
 t/helper/test-scrap-cache-tree.c |  2 +-
 wt-status.c                      |  7 ++++---
 22 files changed, 49 insertions(+), 36 deletions(-)

-- 
2.11.0-274-g0631465056