bff still references master branch

[kuannie1]

No description provided.

[mbarrien]

To elaborate a bit more, there are hard coded references to master branch at https://github.com/chanzuckerberg/bff/blob/401caa5500365de3e2db24d78363fae0b6f6a246/pkg/util/git.go and
https://github.com/chanzuckerberg/bff/blob/a2aecc4a3d2fe807e23e20a2af16c99dfbb2f3ba/cmd/bump.go which need to be made configurable for a default branch name that doesn't match master.

In theory this could be extractable by git symbolic-ref refs/remotes/origin/HEAD (which reads the file .git/refs/remotes/origin/HEAD), but unfortunately if you change the default branch in GitHub, a git fetch/git pull doesn't update the default branch in that file (verified this behavior by running this). A user may need to manually reset it by running something like git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/main.

Either being able to read that file (and documenting what the user needs to do to reset the default branch), or allowing a config file/env var to supply the the default branch would be useful.

References:
https://stackoverflow.com/questions/45811971/warning-ignoring-broken-ref-refs-remotes-origin-head
https://stackoverflow.com/questions/18726037/what-determines-default-branch-after-git-clone

[mbarrien]

https://stackoverflow.com/questions/51274430/change-from-master-to-a-new-default-branch-git says that git remote set-head origin -a will update the HEAD reference if the master changes, and I tested that this works. Take that into account in any documentation/code changes to support this.