Bug in merge-base

  Hello,

  I've hit a strange bug in merge-base I don't want to debug now. ;-)
I've been doing my regular git pull test from my main branch, but
suddenly git merge wanted to do a tree merge instead of fast-forward.
What went wrong?

  The commits tree looks like:

  36c764 -- 808162 -- ...... -- 8e08e7
  5b53d3 -'

(see the rev-tree output at http://pasky.or.cz/~pasky/dev/git/stuff/rev-tree)

  The problem is, merge-base hints me wrong:

  $ merge-base 8e08e7 808162
5b53d3

instead of 808162.

  Thanks,