Jeff King authored Mar 10, 2019 and Junio C Hamano committed Mar 11, 2019

If you use "log -L" with an output format like "--raw" or "--stat",
we'll silently ignore the format and just output the normal patch.
Let's detect and complain about this, which at least tells the user
what's going on.

The tests here aren't exhaustive over the set of all formats, but it
should at least let us know if somebody breaks the format-checking.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>