contrib/showstack.py

tests: make chunk header of external diff glob-ed for portability

Before this patch, some tests using external "diff" command via
extdiff extension fail on Solaris, because system standard "diff" (=
/usr/bin/diff) on Solaris always formats chunk header in the style
below:

  @@ -X.x +Y.y @@

even though "diff" on Linux sometimes omits ".x" and/or ".y" in it.

This patch makes chunk header of external diff glob-ed for portability
of tests, and adds check-code.py rules to detect such diff output in
tests.

This patch also changes "hg diff" output in test-subrepo-git to
simplify detection rules, even though it is certainly portable because
these lines are generated by "git" command.

This patch is a part of making tests using external "diff" portable,
and tests below aren't yet portable even after this patch.

  test-largefiles-update.t
  test-subrepo-deep-nested-change.t

# 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