worker: print traceback for uncaught exception unconditionally This is what a Python interpreter would do if there were no os._exit().

worker: propagate exit code to main process Follows up 86cd09bc13ba.

dispatch: print traceback in scmutil.callcatch() if --traceback specified Otherwise, traceback wouldn't be printed for a known exception occurred in worker processes.

dispatch: mark callcatch() as a private function

templatefilters: fix crash by string formatting of '{x|splitlines}' Before, it crashed because mapping['templ'] was missing. As it didn't support the legacy list template from the beginning, we can simply use hybridlist().

templatekw: factor out showdict() helper Make it less cryptic for common cases.

templatekw: have showlist() take mapping dict with no **kwargs expansion (API) See the previous commit for why. splitlines() does not pass a mapping dict, which would probably mean the legacy template didn't work from the beginning.

templatekw: change _showlist() to take mapping dict with no **kwargs expansion There was a risk that a template keyword could conflict with an argument name (e.g. 'name', 'values', 'plural', etc.) Let's make it less magical.