tests/unwrap-message-id.py

perf: drop an unused variable assignment

Caught by PyCharm.  A different formatter is created below in `_displaystats()`.

Differential Revision: https://phab.mercurial-scm.org/D7744

from __future__ import absolute_import, print_function

import re
import sys

print(re.sub(r"(?<=Message-Id:) \n ", " ", sys.stdin.read()), end="")