how to list commits on branch since last merge

[Jay Soffian <jaysoffian@gmail.com>]

Given this history:

o---o---x---o---...    foo
 \       \
  o---o---m---o---...  bar

I want to list the commits on bar newer than merge m (the last merge
from foo). merge-base returns x.

I feel like I'm going to face-palm upon reply, but the only way I see
to do it is:

  $ git rev-list --ancestry-path $(git merge-base foo bar)..bar

Or by greping the output of rev-list --merges --parents foo..bar
looking for the merge base.

I must be missing something obvious, since this feels like it should
be a common operation. :-)

j.