t / t4013 / diff.diff-tree_-c_masteron commit builtin-am: check for valid committer ident (5e4f9cf)
   1$ git diff-tree -c master
   259d314ad6f356dd08601a4cd5e530381da3e3c64
   3::100644 100644 100644 cead32e925b1420c84c14cbf7cf755e7e45af8ad 7289e35bff32727c08dda207511bec138fdb9ea5 992913c5aa0a5476d10c49ed0f21fc0c6d1aedf3 MM    dir/sub
   4::100644 100644 100644 b414108e81e5091fe0974a1858b4d0d22b107f70 f4615da674c09df322d6ba8d6b21ecfb1b1ba510 10a8a9f3657f91a156b9f0184ed79a20adef9f7f MM    file0
   5$