Fix image proxy from throwing 404 on initial image load.
Fix image proxy from throwing 404 on initial image load.

Credit: https://www.simplemachines.org/community/index.php?topic=553914.msg3926081#msg3926081

Signed-off-by: Colin Schoen <db9f0369fca3c6c82031fd33aeed6b155234ccfe@berkeley.edu>

StealthWombat/SMF2.1-more-forkery,StealthWombat/SMF2.1-more-forkery