juju: fix error message check
juju: fix error message check

In Go tip, the error message has changed, so
allow both old and new messages.

R=TheMue
CC=
https://codereview.appspot.com/6849101

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