contrib/showstack.py

hook: flush stdout before restoring stderr redirection

There was a similar issue to 8b011ededfb2. If an in-process hook writes
to stdout, the data may be buffered. In which case, stdout must be flushed
before restoring its file descriptor. Otherwise, remaining data would be sent
over the ssh wire and corrupts the protocol.

Note that this is a different redirection from the one I've just removed.

# showstack.py - extension to dump a Python stack trace on signal
#
# binds to both SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs)

from __future__ import absolute_import
import signal
import sys
import traceback

def sigshow(*args):
    sys.stderr.write("\n")
    traceback.print_stack(args[1], limit=10, file=sys.stderr)
    sys.stderr.write("----\n")

def extsetup(ui):
    signal.signal(signal.SIGQUIT, sigshow)
    try:
        signal.signal(signal.SIGINFO, sigshow)
    except AttributeError:
        pass