Currently, to use the plugin manager as an easy method of running one-off scripts that DO NOT need to be re-run at boot time, the script needs to exit with a non-zero return code to force pluginMan to not copy the .plg to /boot/config/plugins.
The trigger for this is a new <PLUGIN> attribute of "noInstall" When its value is non-null, the .plg will not get saved to /bot/config/plugins, but the .plg can still exit with a proper zero return code.
Admittedly, not too much call for this, but it would have come in handy for my Support / Project template update script for 6.4.1-rc2
plugincheck script doesn't check if a plugin is still installed. Only if the .plg still exists in /tmp/plugins. Update notices will happen until a reboot is issued
