t / t4013 / diff.show_initialon commit sha1_file: link() returns -1 on failure, not errno (e32c0a9)
   1$ git show initial
   2commit 444ac553ac7612cc88969031b02b3767fb8a353a
   3Author: A U Thor <author@example.com>
   4Date:   Mon Jun 26 00:00:00 2006 +0000
   5
   6    Initial
   7$