Here's what I did on my supposed-to-be-stable branch...
% git rebase master
First, rewinding head to replay your work on top of it...
Fast-forwarded alpha-0.3.0 to master.
% git status
# On branch alpha-0.3.0
# Your branch is ahead of 'origin/alpha-0.3.0' by 53 commits.
#
nothing to commit (working directory clean)
% git push
Fetching remote heads...
refs/
refs/heads/
refs/tags/
refs/remotes/
'refs/heads/master': up-to-date
updating 'refs/heads/alpha-0.3.0'
from cc4b63bebb6e6dd04407f8788938244b78c50285
to 83c9191dea88d146400853af5eb7555f252001b0
done
'refs/heads/unstable': up-to-date
Updating remote server info
That was all a mistake as I later realized. I'd like to undo this entire process, and revert the alpha-0.3.0 branch back to what it was.
What should I do?
Answer
You need to make sure that no other users of this repository are fetching the incorrect changes or trying to build on top of the commits that you want removed because you are about to rewind history.
Then you need to 'force' push the old reference.
git push -f origin last_known_good_commit:branch_name
or in your case
git push -f origin cc4b63bebb6:alpha-0.3.0
You may have receive.denyNonFastForwards set on the remote repository. If this is the case, then you will get an error which includes the phrase [remote rejected].
In this scenario, you will have to delete and recreate the branch.
git push origin :alpha-0.3.0
git push origin cc4b63bebb6:refs/heads/alpha-0.3.0
If this doesn't work - perhaps because you have receive.denyDeletes set, then you have to have direct access to the repository. In the remote repository, you then have to do something like the following plumbing command.
git update-ref refs/heads/alpha-0.3.0 cc4b63bebb6 83c9191dea8