tests/testlib/sigpipe-worker.py

attr: vendor 22.1.0

The previous version was 5 years old, and pytype 2022.06.30 started complaining
about various uses (e.g. seeing `mercurial.thirdparty.attr._make._CountingAttr`
instead of `bytearray`).  Hopefully this helps.  Additionally, this has official
python 3.11 support.

The `attrs` package is left out, because it is simply a bunch of *.pyi stubs and
`from attr.X import *`, and that's not how they've been used up to this point.
We'd probably need to customize those anyway to
`from mercurial.thirdparty.attr import *`.

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

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)