When `remote.<name>.branch` is not configured, `git submodule update`
currently falls back to using the branch name `master`. A much better
idea, however, is to use the remote `HEAD`: on all Git servers running
reasonably recent Git versions, the symref `HEAD` points to the main
branch.
Note: t7419 demonstrates that there _might_ be use cases out there that
_expect_ `git submodule update --remote` to update submodules to the
remote `master` branch even if the remote `HEAD` points to another
branch. Arguably, this patch makes the behavior more intuitive, but
there is a slight possibility that this might cause regressions in
obscure setups.
Even so, it should be okay to fix this behavior without anything like a
longer transition period:
- The `git submodule update --remote` command is not really common.
- Current Git's behavior when running this command is outright
confusing, unless the remote repository's current branch _is_ `master`
(in which case the proposed behavior matches the old behavior).
- If a user encounters a regression due to the changed behavior, the fix
is actually trivial: setting `submodule.<name>.branch` to `master`
will reinstate the old behavior.
Helped-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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