worker/firewaller: Fix obsolete error message
worker/firewaller: Fix obsolete error message

bz2/juju,dimitern/juju,dimitern/juju,howbazaar/juju,frankban/juju,alesstimec/juju,dooferlad/juju,kat-co/juju,anastasiamac/juju,AdamIsrael/juju,bogdanteleaga/juju,anastasiamac/juju,mikemccracken/juju,axw/juju,makyo/juju,perrito666/juju,mjs/juju,AdamIsrael/juju,waigani/juju,bz2/juju,mikemccracken/juju,axw/juju,dooferlad/juju,bac/juju,makyo/juju,frankban/juju,AdamIsrael/juju,bz2/juju,alesstimec/juju,macgreagoir/juju,anastasiamac/juju,perrito666/juju,howbazaar/juju,marcmolla/juju,perrito666/juju,bac/juju,bogdanteleaga/juju,macgreagoir/juju,waigani/juju,howbazaar/juju,macgreagoir/juju,reedobrien/juju,bz2/juju,mjs/juju,marcmolla/juju,mjs/juju,mikemccracken/juju,makyo/juju,mjs/juju,alesstimec/juju,axw/juju,gabriel-samfira/juju,dooferlad/juju,axw/juju,howbazaar/juju,mjs/juju,mjs/juju,gabriel-samfira/juju,dimitern/juju,alesstimec/juju,marcmolla/juju,ericsnowcurrently/juju,axw/juju,AdamIsrael/juju,gabriel-samfira/juju,kat-co/juju,kat-co/juju,makyo/juju,mjs/juju,marcmolla/juju,dooferlad/juju,mikemccracken/juju,ericsnowcurrently/juju,gabriel-samfira/juju,dooferlad/juju,mikemccracken/juju,bogdanteleaga/juju,macgreagoir/juju,frankban/juju,reedobrien/juju,bogdanteleaga/juju,frankban/juju,bac/juju,reedobrien/juju,frankban/juju,waigani/juju,anastasiamac/juju,ericsnowcurrently/juju,perrito666/juju,kat-co/juju,dimitern/juju,alesstimec/juju,kat-co/juju,ericsnowcurrently/juju,bac/juju,gabriel-samfira/juju,perrito666/juju,dimitern/juju,bac/juju,marcmolla/juju,reedobrien/juju,bz2/juju,howbazaar/juju,anastasiamac/juju,reedobrien/juju,ericsnowcurrently/juju,macgreagoir/juju,waigani/juju