contrib/showstack.py

merge: add stubs for preprocess and conclude steps of merge driver

The exact semantics for what should happen (particularly with respect to error
handling) are still a bit hard to pin down, so I think it's better to
experiment with it as an extension for now. For now this stub will act as a
convenient point for extensions to hook on.

# 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