Aha, found a gdb incantation that worked:
wing-commander /tmp% gdb ./upstart/usr/lib/debug/sbin/init.debug ./upstart-segfault/core.10726
Aha, found a gdb incantation that worked:
wing-commander /tmp% gdb ./upstart/ usr/lib/ debug/sbin/ init.debug ./upstart- segfault/ core.10726