tests/testlib/sigpipe-worker.py

test-bundle: split some variant in there own section

Same rational as the previous commit about test-bundle.t. These line are quite
volatile and having dedicated block will make their update clearer and simpler.

Differential Revision: https://phab.mercurial-scm.org/D12076

#!/usr/bin/env python3
#
# This is literally `cat` but in python, one char at a time.
#
# see sigpipe-remote.py for details.
from __future__ import print_function

import io
import os
import sys


if isinstance(sys.stdout.buffer, io.BufferedWriter):
    print('SIGPIPE-WORKER: script need unbuffered output', file=sys.stderr)
    sys.exit(255)

while True:
    c = os.read(sys.stdin.fileno(), 1)
    os.write(sys.stdout.fileno(), c)