We implicitly rely on `the_repository` in `parse_loose_ref_contents()` by calling `parse_oid_hex()`. Convert the function to instead use `parse_oid_hex_algop()` and have callers pass in the hash algorithm to use. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>