[PATCH 0/2] Optionally support push options on up-to-date branches

[Christopher Lindee <christopher.lindee@webpros.com>]

Some Git servers can take actions on a branch using push options; to do this,
the branch ref must be passed along with the push options.  However, if the
branch is up-to-date, then Git submits push options without any refs, so the
server is not given a branch to act upon and the push options become no-ops.

This means a user who does the following

    $ git commit
    $ git push -o option remote branch  # Performs option

will have a very different experience from a user who does

    $ git commit
    $ git push remote branch
    $ git push -o option remote branch  # No-op

The latter could easily happen when a user forgets to add an appropriate option
on push, but could also happen intentionally when a user wants to back up their
changes to a remote and then later chooses to submit those changes with a push
option (e.g. one that creates a pull request) to the same remote.

To work around this issue, the user needs to re-write history between the two
push commands in some way, either through force pushing a temporary value to
the remote or by amending their commit to change the timestamp.  Either can
impact users who pull from the server, as well as automated systems triggered
by a post-receive hook.  With these potential side-effects, this workaround can
be a bad option in some setups.

This changeset proposes to address this issue by adding an option to `push` and
`send-pack` that, when specified, will send refs where the old-oid and new-oid
are identical - instead of silently skipping these refs.  The first commit
introduces the `--send-up-to-date` option to toggle this behavior, while the
second commit updates the commands to output an `(up-to-date)` notice for each
branch with an identical old-oid and new-oid.

Notably, the `--force` option will not send a ref when the remote is up-to-date.

Chris Lindee (2):
  Teach send-pack & push to --send-up-to-date refs
  Add transport message for up-to-date references

 Documentation/git-push.txt      | 8 +++++++-
 Documentation/git-send-pack.txt | 7 +++++++
 builtin/push.c                  | 1 +
 builtin/send-pack.c             | 4 ++++
 send-pack.c                     | 2 +-
 send-pack.h                     | 3 ++-
 transport-helper.c              | 7 ++++++-
 transport.c                     | 3 +++
 transport.h                     | 1 +
 9 files changed, 32 insertions(+), 4 deletions(-)
        

base-commit: 3c2a3fdc388747b9eaf4a4a4f2035c1c9ddb26d0
-- 
2.38.1