Print driver exception on retype
Print driver exception on retype

If the driver raises an exception, make sure it is printed. Also change
the logging level from info to error because an exception should not be
thrown under normal conditions.

Change-Id: I003959c3f7c7667124ef61911587012fd4e1d667
Closes-Bug: #1268294

Akrog/cinder,openstack/cinder,tlakshman26/cinder-new-branch,openstack/cinder,Paul-Ezell/cinder-1,dims/cinder,JioCloud/cinder,phenoxim/cinder,spring-week-topos/cinder-week,hguemar/cinder,potsmaster/cinder,Accelerite/cinder,bswartz/cinder,Paul-Ezell/cinder-1,abusse/cinder,Datera/cinder,github-borat/cinder,alex8866/cinder,ge0rgi/cinder,Thingee/cinder,redhat-openstack/cinder,petrutlucian94/cinder,takeshineshiro/cinder,duhzecca/cinder,leilihh/cinder,sasukeh/cinder,scality/cinder,scottdangelo/RemoveVolumeMangerLocks,alex8866/cinder,Thingee/cinder,cloudbase/cinder,manojhirway/ExistingImagesOnNFS,JioCloud/cinder,eharney/cinder,NeCTAR-RC/cinder,Accelerite/cinder,nexusriot/cinder,saeki-masaki/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,spring-week-topos/cinder-week,tlakshman26/cinder-new-branch,apporc/cinder,phenoxim/cinder,saeki-masaki/cinder,nexusriot/cinder,j-griffith/cinder,sasukeh/cinder,abusse/cinder,NeCTAR-RC/cinder,Akrog/cinder,potsmaster/cinder,CloudServer/cinder,eharney/cinder,CloudServer/cinder,nikesh-mahalka/cinder,manojhirway/ExistingImagesOnNFS,blueboxgroup/cinder,Hybrid-Cloud/cinder,Nexenta/cinder,julianwang/cinder,apporc/cinder,tlakshman26/cinder-https-changes,winndows/cinder,bswartz/cinder,Thingee/cinder,mahak/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,winndows/cinder,NetApp/cinder,redhat-openstack/cinder,NetApp/cinder,Hybrid-Cloud/cinder,dims/cinder,rakeshmi/cinder,duhzecca/cinder,rakeshmi/cinder,hguemar/cinder,Nexenta/cinder,tlakshman26/cinder-https-changes,github-borat/cinder,scottdangelo/RemoveVolumeMangerLocks,petrutlucian94/cinder,mahak/cinder,leilihh/cinder,nikesh-mahalka/cinder,julianwang/cinder,j-griffith/cinder,scality/cinder,Datera/cinder,takeshineshiro/cinder,blueboxgroup/cinder,cloudbase/cinder