provision/docker: fix error handling in docker-node-add. fixes #901
provision/docker: fix error handling in docker-node-add. fixes #901

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