tests/testlib/sigpipe-worker.py

dirstate: deal with read-race for python code using rust object

If we cannot read the dirstate data, this is probably because a writing process
wrote it under our feet. So refresh the docket and try again a handful of time.

#!/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)