How to tell which branch a github commit was for?

Question

On github, when I view a commit, it shows me the commit message and the changes, along with any comments at the bottom. However, it doesn't tell me what branch the commit was checked in to. Even if I 'Browse Code', it is browsing the code for a particular 'tree' (presumably the state of the code when the commit was made), rather than for a particular branch.

I know that commits in git aren't intrinsically linked to a branch, but surely they are always going to be first committed into a particular branch? Isn't the commit tagged with that branch, and can I view which branch it was somehow?

Answer 1

OK, the answer to this question, fundamentally, is: there is no definitive way to tell. Mercurial actually tags commits with the name of the branch they were checked in to, but git simply doesn't; apparently, it isn't considered important what the name of the branch was. This was a design decision and it doesn't look like it's going to change.

Answer 2

If you know the commit number, you can simply do this

git branch --contains <commit>

This should give you the branch name in which the commit was made.

UPDATE: On GitHub specifically, you now can see the branch a given commit is part of. The blog post "Branch and Tag Labels For Commit Pages" details:

If the commit is not on the default branch, the indicator will show the branches which contain the commit. If the commit is part of an unmerged pull request, a link will be shown.

Answer 3

From git help branch:

With --contains, shows only the branches that contain the named commit (in other words, the branches whose tip commits are descendants of the named commit).

With --merged, only branches merged into the named commit (i.e. the branches whose tip commits are reachable from the named commit) will be listed.

With --no-merged only branches not merged into the named commit will be listed. If the argument is missing it defaults to HEAD (i.e. the tip of the current branch).