The EVENT_UPDATE_BUG event signal is currently happening before the bug gets updated, but after the switch/case statement that check the status and will close the bug if the conditions are met.
This does not allow the plugins to take any action prior to the bug being closed, such as checking for "Plugin conditions" to be met before the "update" action is taken.

The event signal should be moved to before bug_resolve() and bug_close() are called.