testing/provisioner: improve error message
testing/provisioner: improve error message

tsuru/tsuru,kgrvamsi/tsuru,mderaldo/tsuru,cgvarela/tsuru,gwmoura/tsuru,jblancett/tsuru,guilhermebr/tsuru,ArxdSilva/tsuru,4eek/tsuru,cezarsa/tsuru,tuxmonteiro/tsuru,ArxdSilva/tsuru,RichardKnop/tsuru,guilhermebr/tsuru,ArxdSilva/tsuru,tsuru/tsuru,hcxiong/tsuru,4eek/tsuru,guilhermebr/tsuru,cgvarela/tsuru,Endika/tsuru,RichardKnop/tsuru,jblancett/tsuru,kgrvamsi/tsuru,mderaldo/tsuru,hugoantunes/tsuru,guilhermebr/tsuru,ArxdSilva/tsuru,Endika/tsuru,tuxmonteiro/tsuru,firebitsbr/tsuru,cezarsa/tsuru,tuxmonteiro/tsuru,ggarnier/tsuru,tsuru/tsuru,kgrvamsi/tsuru,gwmoura/tsuru,hugoantunes/tsuru,ggarnier/tsuru,Endika/tsuru,cgvarela/tsuru,mderaldo/tsuru,tsuru/tsuru,gciotta/tsuru,hcxiong/tsuru,ggarnier/tsuru,cezarsa/tsuru,firebitsbr/tsuru,gwmoura/tsuru,cezarsa/tsuru,RichardKnop/tsuru,jblancett/tsuru,gciotta/tsuru,hcxiong/tsuru,ggarnier/tsuru,gciotta/tsuru,firebitsbr/tsuru,4eek/tsuru