contrib/showstack.py

update: introduce a 'UpdateAbort' exception

The 'postincoming' function used by 'hg pull --update' and 'hg unbundle' is
catching 'Abort' exceptions to intercept failed update. This feel a bit too
wide to me, so I'm introducing a more precise exception to specify update
destination issues.

# 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