t / t4013 / diff.diff-tree_-c_--abbrev_masteron commit run-command: forbid using run_command with piped output (c29b396)
   1$ git diff-tree -c --abbrev master
   259d314ad6f356dd08601a4cd5e530381da3e3c64
   3::100644 100644 100644 cead32e... 7289e35... 992913c... MM      dir/sub
   4::100644 100644 100644 b414108... f4615da... 10a8a9f... MM      file0
   5$