ACTIN-3460: Add script to clean git branches

[matt-froggatt]

Wrote this to delete stale branches on my local git, added it to scripts because I felt it might be useful to someone else.

[nedleitch]

Seems fine, I might call it git-clean-stale-branches or something similarly more-descriptive.

[nedleitch]

Nit here, I don't think you need the <(...) construct, which presents a file descriptor for the given command output, because mapfile is meant to take stdin. In fact I thought you had to specify -u for that?

While this may (or may not...) work, I'd expect to see either:

git branch -vv | grep ': gone]' | awk '{print $1}' | mapfile -t MERGED_DELETED_BRANCHES

or

mapfile -t MERGED_DELETED_BRANCHES < $(git branch ...)

[matt-froggatt]

Seems I can't use mapfile -t MERGED_DELETED_BRANCHES < $(git branch ...) since < to redirect to stdin expects a file descriptor, and I can't use git branch -vv | grep ': gone]' | awk '{print $1}' | mapfile -t MERGED_DELETED_BRANCHES because it scopes the MERGED_DELETED_BRANCHES variable to the pipeline. I could do mapfile -t MERGED_DELETED_BRANCHES <<< $(git branch ...) but it doesn't feel much better than what's there already.

[nedleitch]

Fair enough. Maybe the GNU version behaves differently. Still fine to merge :)