Not an Upstart bug; upstart is quite compatible with sysvinit in this regard. Running shutdown while an existing one is running is not permitted; gdm should cancel the existing shutdown first (or actually tell you the system is shutting down already and give you a countdown or option to proceed anyway)
Not an Upstart bug; upstart is quite compatible with sysvinit in this regard. Running shutdown while an existing one is running is not permitted; gdm should cancel the existing shutdown first (or actually tell you the system is shutting down already and give you a countdown or option to proceed anyway)