t / t5100 / rfc2047-info-0004on commit tree-diff: convert diff_root_tree_sha1 to struct object_id (7b8dea0)
   1Author: Nathaniel Borenstein (םולש ןב ילטפנ)
   2Email: nsb@thumper.bellcore.com
   3Subject: Test of new header generator
   4