markpasc (markpasc) wrote,
markpasc
markpasc

Recovering from "(no branch)" during a git rebase

I was using git rebase to merge changesets from one subversion repository onto code from a completely different repository. Figuring out multiple svn-remotes and the attendant issues was fun1, though once I figured out I did want to rebase, which onto what, how to delete a remote branch, and how to use rebase --interactive to edit git svn’s ported commit messages, it worked pretty well. But that’s not important.

During the rebase, I ended up off the branch I was trying to do the merge “in,” where git branch said I was on (no branch). However, like everyone else on the internet, I blithely continued past that point. How do I recover from (no branch) without losing the completed rebase?

mpaschal@mpaschal-mt:~/svn/mt/git$ git branch -a
* (no branch)
  atompub
  master
  git-svn
  github/master
  trunk

Of the search results I consulted, Mark Guzman best described what happened:

Little did I know that I had entered the “(no branch)” state. At this point I was pretty much gunning to create orphaned blobs, commits and other such items.

So (no branch) is when HEAD is a commit that is no longer one of the leading branch commits (which is what it means to be “on a branch”). If as in this case I want atompub to match HEAD, I have to git merge the outstanding HEAD commits over to atompub. That works fine since the new commits are changesets atop atompub in the first place; it’s as though I’m on a branch of atompub, only I never explicitly branched, so it doesn’t have a name. Instead I have to refer to it by the commit ID.

As I hadn’t switched back to the real branch yet, I didn’t have to recover my nameless HEAD commit the way Mark did. Instead I could look directly at the log:

mpaschal@mpaschal-mt:~/svn/mt/git$ git log -1 --pretty=oneline
658b8173ab396c7bb765f990c2bc2fdc7d639c86 Merged all ...

Then switch and merge:

mpaschal@mpaschal-mt:~/svn/mt/git$ git checkout atompub
Switched to branch "atompub"
mpaschal@mpaschal-mt:~/svn/mt/git$ git merge 658b817
Updating 461f2f7..658b817
Fast forward
  ...

It’s like magic!2

1 Not actually fun.

2 It’s a long incantation you have to research to discover, and getting it wrong can have disastrous consequences.

Tags: git
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