Images: fix invalid exception message
Images: fix invalid exception message

Commit 6f9ed562d5f6df1dc16029dcaffd4d2e6601099d added an
incomplete exception message.

TrivialFix

Change-Id: I4b0a54a037d9400b96992c4748fa6e31de5f6854

zhimin711/nova,mikalstill/nova,edulramirez/nova,cloudbase/nova,mmnelemane/nova,iuliat/nova,openstack/nova,bigswitch/nova,whitepages/nova,rajalokan/nova,ted-gould/nova,varunarya10/nova_test_latest,devendermishrajio/nova_test_latest,takeshineshiro/nova,akash1808/nova_test_latest,CCI-MOC/nova,zhimin711/nova,alaski/nova,yosshy/nova,JianyuWang/nova,sebrandon1/nova,fnordahl/nova,CEG-FYP-OpenStack/scheduler,barnsnake351/nova,isyippee/nova,cloudbase/nova,j-carpentier/nova,ruslanloman/nova,LoHChina/nova,raildo/nova,felixma/nova,CEG-FYP-OpenStack/scheduler,zzicewind/nova,klmitch/nova,vmturbo/nova,Juniper/nova,noironetworks/nova,rahulunair/nova,ruslanloman/nova,Juniper/nova,scripnichenko/nova,JioCloud/nova_test_latest,klmitch/nova,hanlind/nova,whitepages/nova,barnsnake351/nova,klmitch/nova,openstack/nova,dims/nova,apporc/nova,ted-gould/nova,mahak/nova,NeCTAR-RC/nova,Francis-Liu/animated-broccoli,cyx1231st/nova,BeyondTheClouds/nova,nikesh-mahalka/nova,jianghuaw/nova,gooddata/openstack-nova,zzicewind/nova,mikalstill/nova,phenoxim/nova,rahulunair/nova,rajalokan/nova,jianghuaw/nova,mikalstill/nova,mahak/nova,yosshy/nova,cernops/nova,isyippee/nova,MountainWei/nova,BeyondTheClouds/nova,rajalokan/nova,watonyweng/nova,vmturbo/nova,sebrandon1/nova,edulramirez/nova,JianyuWang/nova,hanlind/nova,watonyweng/nova,LoHChina/nova,cernops/nova,Juniper/nova,devendermishrajio/nova,jianghuaw/nova,apporc/nova,TwinkleChawla/nova,jianghuaw/nova,bigswitch/nova,Francis-Liu/animated-broccoli,shail2810/nova,takeshineshiro/nova,shail2810/nova,mmnelemane/nova,JioCloud/nova_test_latest,dims/nova,gooddata/openstack-nova,devendermishrajio/nova,hanlind/nova,sebrandon1/nova,gooddata/openstack-nova,raildo/nova,devendermishrajio/nova_test_latest,varunarya10/nova_test_latest,klmitch/nova,felixma/nova,gooddata/openstack-nova,mahak/nova,akash1808/nova_test_latest,iuliat/nova,scripnichenko/nova,cernops/nova,j-carpentier/nova,noironetworks/nova,vmturbo/nova,fnordahl/nova,cyx1231st/nova,TwinkleChawla/nova,vmturbo/nova,alaski/nova,nikesh-mahalka/nova,phenoxim/nova,NeCTAR-RC/nova,Juniper/nova,rahulunair/nova,BeyondTheClouds/nova,cloudbase/nova,rajalokan/nova,openstack/nova,CCI-MOC/nova,MountainWei/nova