Jeff King [off-list ref] writes:
One problem there is that the prefixes are ambiguous (e.g., Jacob Keller
shares with me, and I think at least one other over the years). You
could look at the author of the tip commit, but that's not always right
(and in fact, counting just merged topics misses bug-fixes that get
applied directly on top of other people's topics).
Yes, a fix by somebody else to a bug that was recently introduced is
safest to apply to the original topic and merge down; that way makes
it more difficult to merge the original topic to older maintenance
track(s) without the fix by mistake. So a "topic" with commits from
multiple people is not all that unusual.
Thanks.