"Find a merge base in preparation for an octopus merge."

I think that should at least be better than what you got now.

Also, I'm really sorry if I somehow seemed rude or made you feel bad about your english. This is absolutely not what I intended to do. We're all very grateful for your pull request and the effort you put in!

I just want to make sure that other people will be able to tell the difference between this function and `git_merge_base_many` without having to go through the libgit2 or git.git source code.