t / t5100 / msg0010on commit cache.h: document `write_locked_index()` (8dc3834)
   1"Subject: " isn't in the static array "header", and thus
   2memcmp("Subject: ", header[i], 7) will never match.
   3
   4Signed-off-by: Lukas Sandström <lukass@etek.chalmers.se>
   5Signed-off-by: Junio C Hamano <gitster@pobox.com>