contrib/showstack.py

test-amend: match output using conditional test case name

D466 (6cc8f848b4c3) allows output to be conditionally matched by test name.
This patch changes test-amend.t to use that feature, instead of duplicating
`hg amend` command or use `-q` to silence its output.

Differential Revision: https://phab.mercurial-scm.org/D601

# 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