anchor.diff:  
   prerequisites() ->
       [
  -     { "docker in $PATH?",
  -       fun (_Config) ->
  -               {done, 0, <<"Docker", _/bytes>>} = erlsh:oneliner("docker -v")
  -       end}
  +     { "docker in $PATH", fun (_Config) -> {_, _, <<"Docker", _/bytes>>} = sh("docker -v") end },
  +     { "git in $PATH", fun (_) -> {_, _, <<"usage: git", _/bytes>>} = sh("git --help") end }
       ].
   
   end_per_suite(_Config) ->
  
positive.code:     start_container(Name, Args),
      try
          sh(["docker exec ", Name, " echo a"]),
          ct:fail("not implemented yet")
      after
          sh("docker stop " ++ Name)
  
negative.code:         sh(["docker ps | grep ", Name, " | grep Up"]),
          true
      catch _:_ -> false end.
  
  current_git_commit() ->
      {_, _, R} = sh("git rev-parse HEAD").
  