The test preq->packfile != NULL is always true. If packfile was
actually NULL when entering this function the ftell() above would
crash out with a SIGSEGV, resulting in never reaching this point.
Simplify the code by just removing the conditional.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>