contrib/showstack.py

tests: change blackbox test to work cross platform

While it is not easy to make a file 000 on Windows, you can
emulate most of the behaviors by replacing the file with a directory.

Also corrects test description to properly indicate that failing to
read from the log is fatal.

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

import sys, signal, 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