Junio C Hamano [off-list ref] writes:
And this makes "git log" to take common diff-tree options, so
that it can be used as "git whatchanged".
BTW, this is *not* "whatchanged" in that it does not omit the
log when there is no diff output. It may not matter much --
when we give paths limiter to the command, the commits that are
shown are already limited by those paths limiter.