There are both merge and rebase branches in the logic, and previously
both had to handle fast-forwarding. Merge handled that implicitly
(because git merge handles it directly), while in rebase it was
explicit. Given that the --ff-only flag is meant to override any
--rebase or --no-rebase, make the code reflect that by handling
--ff-only before the merge-vs-rebase logic.
It turns out that this also fixes a bug for submodules. Previously,
when --ff-only was given, the code would run `merge --ff-only` on the
main module, and then run `submodule update --recursive --rebase` on the
submodules. With this change, we still run `merge --ff-only` on the
main module, but now run `submodule update --recursive --checkout` on
the submodules. I believe this better reflects the intent of --ff-only
to have it apply to both the main module and the submodules.
(Sidenote: It is somewhat interesting that all merges pass `--checkout`
to submodule update, even when `--no-ff` is specified, meaning that it
will only do fast-forward merges for submodules. This was discussed in
commit a6d7eb2c7a ("pull: optionally rebase submodules (remote submodule
changes only)", 2017-06-23). The same limitations apply now as then, so
we are not trying to fix this at this time.)
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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