Checking if a Git branch has been merged into master when SQUASHED?

branch, git, github, merge, squash

Solution

Here's one approach:

- Use the GitHub API to get the HEAD SHA for all merged pull requests.

- Match these SHAs against local branches.

If a local branch's HEAD has corresponds to that of a PR that's been merged, then you can safely delete it. This will work regardless of how the PR was merged (full merge, fast foward, squash and merge).

I implemented this approach in a delete-squashed-branches script. Here's what usage looks like:

(master) $ git branch
  delete-merged-prs
  fixup
  unmerged-branch
* master

(master) $ delete-squashed-branches
Finding local branches which were merged onto origin/master via GitHub...
warning: deleting branch 'delete-merged-prs' that has been merged to
     'refs/remotes/origin/delete-merged-prs', but not yet merged to HEAD.
Deleted branch delete-merged-prs (was 325a42b).
warning: deleting branch 'fixup' that has been merged to
     'refs/remotes/origin/fixup', but not yet merged to HEAD.
Deleted branch fixup (was e54f54b).

(master) $ git branch
  unmerged-branch
* master

(The warnings can be ignored since the branches were merged onto master via Squash & Merge.)

Caveats:

- You'll need to `pip install pygithub` to use the script.

- It will look for local branches that were merged onto `origin/(current branch)`. So you'll want to run it on `master`, `develop` or whatever branch you work off of.

- If you have multiple long-lived branches, this approach won't work very well.

Problem

I'd like to automate cleaning of remote branches. I want to be able to check to see if a branch has been merged into master already. Originally, my plan was to use git merge-base to see the last common commit. However, it turns out that we squash all of our branches as we merge them into master. As this creates a new commit hash, I'm unable to find the common commits between master and my branches. How might I go about determining if a branch has been merged if we've squashed them all when merging? Thanks in advance!

Original source