git alias.stamp definition conflicts with description of action stamps
http://www.catb.org/esr/reposurgeon/reposurgeon.html says:
An action stamp is an RFC3339 timestamp, followed by a '!', followed by an author email address (author rather than committer because that timestamp is not changed when a patch is replayed on to a branch).
But then says
# git stamp <commit-ish> - print a reposurgeon-style action stamp stamp = show -s --format='%cI!%ce'
This uses the committer timestamp and email address.
Which one is correct?