t / t5100 / info0001on commit sha1_file: convert check_sha1_signature to struct object_id (17e6545)
   1Author: A (zzz) U Thor (Comment)
   2Email: a.u.thor@example.com
   3Subject: a commit.
   4Date: Fri, 9 Jun 2006 00:44:16 -0700
   5