provider/local: fix test isolation
provider/local: fix test isolation

don't check real bridge address

mhilton/juju-juju,bz2/juju,jrwren/juju,dimitern/juju,tasdomas/juju,macgreagoir/juju,marcoceppi/juju,tsakas/juju,frobware/juju,frankban/juju-tmp,dooferlad/juju,frankban/juju,sinzui/juju,mikemccracken/juju,mhilton/juju,mikemccracken/juju,mhilton/juju-juju,makyo/juju,cmars/juju,cmars/juju,tasdomas/juju,marcmolla/juju,gabriel-samfira/juju,gabriel-samfira/juju,marcmolla/juju,makyo/juju,ericsnowcurrently/juju,gabriel-samfira/juju,marcoceppi/juju,howbazaar/juju,davecheney/juju,reedobrien/juju,mattyw/juju,frankban/juju,perrito666/juju,reedobrien/juju,bogdanteleaga/juju,perrito666/juju,Altoros/juju-cloudsigma,cloud-green/juju,tsakas/juju,makyo/juju,ericsnowcurrently/juju,frobware/juju,marcoceppi/juju,alesstimec/juju,davecheney/juju,tsakas/juju,mhilton/juju-juju,axw/juju,thomnico/juju,mikemccracken/juju,voidspace/juju,wwitzel3/juju,waigani/juju,davecheney/juju,sinzui/juju,mattyw/juju,rogpeppe/juju,bac/juju,mjs/juju,reedobrien/juju,gabriel-samfira/juju,mjs/juju,ericsnowcurrently/juju,thomnico/juju,anastasiamac/juju,perrito666/juju,waigani/juju,mjs/juju,mhilton/juju,macgreagoir/juju,cherylj/juju,sinzui/juju,axw/juju,dimitern/juju,alesstimec/juju,bogdanteleaga/juju,Altoros/juju-cloudsigma,jrwren/juju,rogpeppe/juju,wwitzel3/juju,cloud-green/juju,marcmolla/juju,voidspace/juju,tych0/juju,cherylj/juju,fwereade/juju,kat-co/juju,frankban/juju,frankban/juju-tmp,bac/juju,axw/juju,anastasiamac/juju,cherylj/juju,mjs/juju,cloud-green/juju,AdamIsrael/juju,reedobrien/store,mhilton/juju,fwereade/juju,voidspace/juju,howbazaar/juju,cmars/juju,tych0/juju,perrito666/juju,AdamIsrael/juju,bac/juju,frankban/juju-tmp,thomnico/juju,tych0/juju,axw/juju,bz2/juju,frobware/juju,Altoros/juju-vmware,dooferlad/juju,howbazaar/juju,marcmolla/juju,mjs/juju,bogdanteleaga/juju,macgreagoir/juju,howbazaar/juju,alesstimec/juju,Altoros/juju-cloudsigma,kat-co/juju,sinzui/juju,howbazaar/juju,fwereade/juju,mjs/juju,mikemccracken/juju,alesstimec/juju,bogdanteleaga/juju,anastasiamac/juju,macgreagoir/juju,kat-co/juju,axw/juju,cherylj/juju,davecheney/juju,bz2/juju,mjs/juju,ericsnowcurrently/juju,bz2/juju,dooferlad/juju,anastasiamac/juju,rogpeppe/juju,Altoros/juju-cloudsigma,dimitern/juju,frankban/juju-tmp,bac/juju,mhilton/juju-juju,Altoros/juju-vmware,waigani/juju,ericsnowcurrently/juju,mattyw/juju,frankban/juju,fwereade/juju,dooferlad/juju,mattyw/juju,mikemccracken/juju,marcmolla/juju,tasdomas/juju,mhilton/juju,kat-co/juju,Altoros/juju-vmware,cloud-green/juju,wwitzel3/juju,marcoceppi/juju,makyo/juju,tasdomas/juju,AdamIsrael/juju,dimitern/juju,thomnico/juju,bz2/juju,waigani/juju,cmars/juju,AdamIsrael/juju,anastasiamac/juju,voidspace/juju,dooferlad/juju,Altoros/juju-vmware,tsakas/juju,alesstimec/juju,tych0/juju,frankban/juju,bac/juju,gabriel-samfira/juju,jrwren/juju,reedobrien/juju,kat-co/juju,perrito666/juju,dimitern/juju,wwitzel3/juju,macgreagoir/juju,reedobrien/juju