CodeQL reports empty `if` blocks that only contain a comment as "futile
conditional". The comment talks about potential plans to turn this into
a warning, but that seems not to have been necessary. Replace the entire
construct with a concise comment.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>