git - For how long can you restore/recover a deleted branch on GitHub?

Question

This is not a question on how to restore lost branches in Github, but rather how long you have to restore a deleted branch through the following user case story:

Within a pull request (often used as a place for code review) the branch can be merged and then deleted, all in the github GUI. Should you choose to delete it, you are given the option with a bold and underlined word, to "restore" the branch.

I suspect this option has a time limit and that github doesn't keep this available indefinitely.

Does github have a time limit on how long you can do this? If it does, what is that time limit?

Answer 1

I asked GitHub Support, this was their response (emphasis mine):

We use a separate ref namespace for all Pull Requests which we use for various things including restoring the branch. Since we keep those [Pull Request] refs indefinitely, there's no time limit on restoring a branch.

You can see these special references in your remote by using the following:

$ git ls-remote | grep pull
From git@github.com:<username>/<remote>.git
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa        refs/pull/1/head
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb        refs/pull/1/merge
cccccccccccccccccccccccccccccccccccccccc        refs/pull/2/head
dddddddddddddddddddddddddddddddddddddddd        refs/pull/2/merge

The references are namespaced under refs/pull/<pull request number>/. The head reference points at the tip of the branch that's being pull requested, i.e. the last commit on the branch. I'm not sure what the merge reference is though.