Fix the detection of the requested snapshot format, which failed for
PATH_INFO URLs since the references to the hashes which describe the
supported snapshot formats weren't dereferenced appropriately.
Signed-off-by: Holger Weiß <holger@zedat.fu-berlin.de> Acked-by: Jakub Narebski <jnareb@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>