anchor.diff:  -spec create_output_dir(file:name()) ->
                                  ok | {error, Reason::term()}.
   create_output_dir(OutputDir) ->
  -    case filelib:is_dir(OutputDir) of
  +    case ec_file:is_dir(OutputDir) of
           false ->
               case rlx_util:mkdir_p(OutputDir) of
                   ok ->
  
positive.code: copy_dir(AppDir, TargetDir, SubDir) ->
      SubSource = filename:join(AppDir, SubDir),
      SubTarget = filename:join(TargetDir, SubDir),
      case filelib:is_dir(SubSource) of
          true ->
              ok = rlx_util:mkdir_p(SubTarget),
              case ec_file:copy(SubSource, SubTarget, [recursive]) of
  
negative.code:             ErtsDir = filename:join([Prefix, "erts-" ++ ErtsVersion]),
              LocalErts = filename:join([OutputDir, "erts-" ++ ErtsVersion]),
              {OsFamily, _OsName} = os:type(),
              case ec_file:is_dir(ErtsDir) of
                  false ->
                      ?RLX_ERROR({specified_erts_does_not_exist, ErtsVersion});
                  true ->
  