Fix exception handling error.
Fix exception handling error.

The exception handler was passing an exception object to the unicode
function, which was not causing it to stringify.

citrix-openstack-build/pbr,openstack-dev/pbr,WiFast/pbr,varunarya10/pbr,JioCloud/pbr,varunarya10/pbr,openstack-dev/pbr,klmitch/pbr,redhat-openstack/pbr,klmitch/pbr,WiFast/pbr,redhat-openstack/pbr,citrix-openstack-build/pbr,openstack-dev/pbr,citrix-openstack-build/pbr,JioCloud/pbr