sm volume driver: fix backend adding failure
sm volume driver: fix backend adding failure

Fixes bug 915085

Change-Id: I908d2090815a90bae479d5caf8516e52fd879c8e

TieWei/nova,Triv90/Nova,maheshp/novatest,devoid/nova,petrutlucian94/nova,citrix-openstack-build/nova,phenoxim/nova,NoBodyCam/TftpPxeBootBareMetal,varunarya10/nova_test_latest,mandeepdhami/nova,whitepages/nova,savi-dev/nova,isyippee/nova,NewpTone/stacklab-nova,zhimin711/nova,Yuriy-Leonov/nova,scripnichenko/nova,JioCloud/nova_test_latest,petrutlucian94/nova_dev,cloudbase/nova,ntt-sic/nova,yatinkumbhare/openstack-nova,devendermishrajio/nova_test_latest,eneabio/nova,rickerc/nova_audit,sileht/deb-openstack-nova,cyx1231st/nova,adelina-t/nova,blueboxgroup/nova,sridevikoushik31/openstack,belmiromoreira/nova,sridevikoushik31/nova,alaski/nova,NewpTone/stacklab-nova,sridevikoushik31/nova,silenceli/nova,vmturbo/nova,Juniper/nova,sridevikoushik31/openstack,cloudbase/nova-virtualbox,takeshineshiro/nova,usc-isi/extra-specs,klmitch/nova,tianweizhang/nova,ewindisch/nova,CCI-MOC/nova,watonyweng/nova,paulmathews/nova,Yusuke1987/openstack_template,fnordahl/nova,CEG-FYP-OpenStack/scheduler,cyx1231st/nova,Metaswitch/calico-nova,dstroppa/openstack-smartos-nova-grizzly,redhat-openstack/nova,apporc/nova,leilihh/nova,Metaswitch/calico-nova,Francis-Liu/animated-broccoli,paulmathews/nova,ted-gould/nova,raildo/nova,dawnpower/nova,devendermishrajio/nova_test_latest,dawnpower/nova,luogangyi/bcec-nova,qwefi/nova,shahar-stratoscale/nova,cloudbase/nova-virtualbox,eayunstack/nova,aristanetworks/arista-ovs-nova,citrix-openstack-build/nova,CloudServer/nova,openstack/nova,tealover/nova,spring-week-topos/nova-week,Triv90/Nova,vmturbo/nova,gspilio/nova,JioCloud/nova,j-carpentier/nova,zhimin711/nova,shail2810/nova,TieWei/nova,belmiromoreira/nova,bclau/nova,ewindisch/nova,fajoy/nova,sridevikoushik31/nova,maoy/zknova,double12gzh/nova,noironetworks/nova,spring-week-topos/nova-week,phenoxim/nova,akash1808/nova,DirectXMan12/nova-hacking,Yuriy-Leonov/nova,mahak/nova,imsplitbit/nova,eharney/nova,cernops/nova,SUSE-Cloud/nova,devendermishrajio/nova,eneabio/nova,mgagne/nova,openstack/nova,Yusuke1987/openstack_template,eneabio/nova,akash1808/nova_test_latest,shail2810/nova,edulramirez/nova,tangfeixiong/nova,tangfeixiong/nova,ted-gould/nova,klmitch/nova,dstroppa/openstack-smartos-nova-grizzly,edulramirez/nova,Francis-Liu/animated-broccoli,ruslanloman/nova,leilihh/novaha,maelnor/nova,cernops/nova,viggates/nova,eayunstack/nova,petrutlucian94/nova_dev,dstroppa/openstack-smartos-nova-grizzly,josephsuh/extra-specs,alvarolopez/nova,CCI-MOC/nova,Juniper/nova,zaina/nova,fajoy/nova,CEG-FYP-OpenStack/scheduler,usc-isi/extra-specs,vladikr/nova_drafts,psiwczak/openstack,eharney/nova,kimjaejoong/nova,thomasem/nova,Juniper/nova,sridevikoushik31/nova,tanglei528/nova,varunarya10/nova_test_latest,dims/nova,CiscoSystems/nova,saleemjaveds/https-github.com-openstack-nova,yrobla/nova,klmitch/nova,joker946/nova,barnsnake351/nova,akash1808/nova,BeyondTheClouds/nova,Triv90/Nova,psiwczak/openstack,sebrandon1/nova,MountainWei/nova,plumgrid/plumgrid-nova,rickerc/nova_audit,yosshy/nova,savi-dev/nova,usc-isi/extra-specs,maoy/zknova,rrader/nova-docker-plugin,hanlind/nova,TwinkleChawla/nova,apporc/nova,affo/nova,virtualopensystems/nova,vmturbo/nova,alaski/nova,houshengbo/nova_vmware_compute_driver,alexandrucoman/vbox-nova-driver,vladikr/nova_drafts,eonpatapon/nova,usc-isi/nova,rahulunair/nova,orbitfp7/nova,ntt-sic/nova,TwinkleChawla/nova,OpenAcademy-OpenStack/nova-scheduler,projectcalico/calico-nova,yrobla/nova,gooddata/openstack-nova,berrange/nova,redhat-openstack/nova,tudorvio/nova,silenceli/nova,mahak/nova,ruslanloman/nova,jianghuaw/nova,angdraug/nova,leilihh/nova,orbitfp7/nova,sacharya/nova,berrange/nova,gooddata/openstack-nova,gspilio/nova,usc-isi/nova,projectcalico/calico-nova,NoBodyCam/TftpPxeBootBareMetal,Stavitsky/nova,mahak/nova,watonyweng/nova,zzicewind/nova,DirectXMan12/nova-hacking,NoBodyCam/TftpPxeBootBareMetal,jianghuaw/nova,affo/nova,bgxavier/nova,rahulunair/nova,alvarolopez/nova,Juniper/nova,mikalstill/nova,aristanetworks/arista-ovs-nova,bclau/nova,CloudServer/nova,rajalokan/nova,devoid/nova,isyippee/nova,DirectXMan12/nova-hacking,JioCloud/nova_test_latest,mmnelemane/nova,maelnor/nova,thomasem/nova,gooddata/openstack-nova,mikalstill/nova,houshengbo/nova_vmware_compute_driver,cloudbase/nova,jianghuaw/nova,CiscoSystems/nova,alexandrucoman/vbox-nova-driver,iuliat/nova,NeCTAR-RC/nova,nikesh-mahalka/nova,tealover/nova,rrader/nova-docker-plugin,bigswitch/nova,rajalokan/nova,josephsuh/extra-specs,plumgrid/plumgrid-nova,rahulunair/nova,aristanetworks/arista-ovs-nova,shahar-stratoscale/nova,akash1808/nova_test_latest,LoHChina/nova,sacharya/nova,josephsuh/extra-specs,JianyuWang/nova,openstack/nova,Stavitsky/nova,badock/nova,rajalokan/nova,viggates/nova,sileht/deb-openstack-nova,joker946/nova,NeCTAR-RC/nova,Brocade-OpenSource/OpenStack-DNRM-Nova,yrobla/nova,BeyondTheClouds/nova,cernops/nova,bigswitch/nova,MountainWei/nova,Tehsmash/nova,shootstar/novatest,houshengbo/nova_vmware_compute_driver,mmnelemane/nova,dims/nova,petrutlucian94/nova,double12gzh/nova,felixma/nova,savi-dev/nova,devendermishrajio/nova,mgagne/nova,scripnichenko/nova,sileht/deb-openstack-nova,saleemjaveds/https-github.com-openstack-nova,badock/nova,zzicewind/nova,usc-isi/nova,JianyuWang/nova,tianweizhang/nova,mikalstill/nova,kimjaejoong/nova,cloudbau/nova,vmturbo/nova,noironetworks/nova,iuliat/nova,LoHChina/nova,yatinkumbhare/openstack-nova,sebrandon1/nova,tudorvio/nova,fajoy/nova,leilihh/novaha,takeshineshiro/nova,NewpTone/stacklab-nova,rajalokan/nova,maheshp/novatest,barnsnake351/nova,zaina/nova,Brocade-OpenSource/OpenStack-DNRM-Nova,sridevikoushik31/openstack,Tehsmash/nova,klmitch/nova,eonpatapon/nova,cloudbau/nova,whitepages/nova,jianghuaw/nova,sebrandon1/nova,JioCloud/nova,felixma/nova,hanlind/nova,psiwczak/openstack,raildo/nova,jeffrey4l/nova,adelina-t/nova,paulmathews/nova,hanlind/nova,maoy/zknova,fnordahl/nova,yosshy/nova,tanglei528/nova,cloudbase/nova,BeyondTheClouds/nova,OpenAcademy-OpenStack/nova-scheduler,jeffrey4l/nova,imsplitbit/nova,shootstar/novatest,virtualopensystems/nova,nikesh-mahalka/nova,maheshp/novatest,luogangyi/bcec-nova,angdraug/nova,gooddata/openstack-nova,SUSE-Cloud/nova,bgxavier/nova,j-carpentier/nova,qwefi/nova,blueboxgroup/nova,gspilio/nova,mandeepdhami/nova