run-tests: display the time it took to install Mercurial
It will help make people aware of this critical step and to assess the time it
takes in various options (like a CI run for example).
#!/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)