De-hardcode the default branch of a remote repo

[yashi]

Should we keep using master as the default? Or, we could determine the default branch of a remote repo using:

git ls-remote --symref $REPO_RUL HEAD

Such as

GitHub

❯ git ls-remote --symref https://github.com/zephyrproject-rtos/zephyr HEAD
ref: refs/heads/main	HEAD
4bd1d39c67dfb4860fbd4f9ccc17e084aa32d763	HEAD

GitLab

❯ git ls-remote --symref https://gitlab.gnome.org/GNOME/glib.git HEAD
ref: refs/heads/main	HEAD
804553b12606a728e9d6fab7b12d1d8f4277f03e	HEAD

cc:

• Document the default revision #820

[henrikbrixandersen]

I would really like us to move towards using the default remote branch instead of guessing on a naming scheme.

[marc-hb]

This was done in 2021 for the manifest, see:

• west init: get default manifest-rev from remote #485

So I don't know yet why it wasn't done for other repos. @mbolivar any relevant memory?

EDIT: #485 was later replaced by e283d99 but I believe that's irrelevant here.

[marc-hb]

I took a quick look and it does not look like a small change. A number of tests in test_manifest.py and test_project.py will also need some updates.