When raised, 'cinder.exception.InvalidVolume' with reason 'Invalid volume: duplicate connectors detected on volume' or 'volume state in error' comes along with a 500 HTTP error. This change aims at returning a 409 HTTP error instead. It takes over patch https://review.opendev.org/c/openstack/cinder/+/856041, taking comments into account. Signed-off-by: David Moreau-Simard <moi@dmsimard.com> Change-Id: I22daff4c806a7c896d2a838b3e2ac0a81113b3e8 (cherry picked from commit67ac0fca89) (cherry picked from commit324204e890)