Fix error on wait_for_response timeout.
Fix error on wait_for_response timeout.

Using pyee 1.0.1 handlers registered with once can't be removed. This handles the value error raised in this case.

MycroftAI/mycroft-core,forslund/mycroft-core,MycroftAI/mycroft-core,linuxipho/mycroft-core,forslund/mycroft-core,Dark5ide/mycroft-core,linuxipho/mycroft-core,Dark5ide/mycroft-core