Note on image locking: Use all_disks.vm_names and all_disks.image_guid to find image id lock it by setting 2 in column images.imagestatus.
Verified with rhevm-4.0.2.1-0.1.el7ev.noarch according to steps to re produce in description. The Warning messages appear as expected in engine.log.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHEA-2016-1743.html