Re: Segfault with merge-tree on multiple Git versions

On Wed, Mar 27, 2013 at 07:45:21PM +0000, John Keeping wrote:

On Wed, Mar 27, 2013 at 02:16:24PM -0500, Jed Brown wrote:

quoted

Charlie Smurthwaite [off-list ref] writes:

quoted

Yes, I would need to be able to do this on a bare repo for my use case. 

And if it's on the server, you don't want this to be observable, so
you don't want HEAD to move around. I don't know a better way than:

  $ git clone --shared -b upstream-branch bare-repo.git /tmp/merge-repo
  $ cd /tmp/merge-repo
  $ git pull URL incoming-branch

Cloning with --shared just writes a path into .git/objects/info/alternatives
and it doesn't need to be on the same file system (unlike --local).

Since 'git merge-tree' just works with trees, it has less information
than 'git merge'.

You could use a temporary index and do something like:

	rm -f TMP_INDEX
	GIT_INDEX_FILE=TMP_INDEX
	export GIT_INDEX_FILE
	git read-tree -m $base $ours $theirs &&
	git merge-index git-merge-one-file -a

then inspect that with "git diff-index --cached $ours".

That is precisely how we do it at GitHub. You probably want to add in
"--aggressive" to your read-tree to cover a few more simple cases. If
there are conflicts, we just bail and say "this can't be merged", and
expect the user to do it themselves using git.

-Peff