Fixups + make the tests work

pre_commit/languages/script.py

@@ -18,7 +18,6 @@ def install_environment(
 def run_hook(repo_cmd_runner, hook, file_args):
     return repo_cmd_runner.run(
         ['xargs', '-0', '{{prefix}}{0}'.format(hook['entry'])] + hook['args'],
-        # TODO: this is duplicated in pre_commit/languages/helpers.py
         stdin=file_args_to_stdin(file_args),
         retcode=None,
         encoding=None,