git-merge-base - Find as good common ancestors as possible for a merge
git-merge-base [--all] <commit> <commit>
"git-merge-base" finds as good a common ancestor as possible between the two commits. That is, given two commits A and B git-merge-base A B will output a commit which is reachable from both A and B through the parent relationship.
Given a selection of equally good common ancestors it should not be relied on to decide in any particular way.
The "git-merge-base" algorithm is still in flux - use the source…
Output all common ancestors for the two commits instead of just one.
Written by Linus Torvalds <firstname.lastname@example.org>
Documentation by David Greaves, Junio C Hamano and the git-list <email@example.com>.
Part of the linkgit:git suite