Live Merge (snapshot deletion) failed because Live Storage Migration was still running

Issue

• A Live Merge (snapshot deletion) failed, leaving a volume in an illegal state.

• The vdsm log on the host on which the VM was running showed that the Live Merge failed because the disk already had an active block job;

jsonrpc.Executor/4::ERROR::2016-12-23 14:01:33,357::vm::4967::virt.vm::(merge) vmId=`db1320ba-817c-4373-872b-2cb142bb303b`::Live merge failed (job: f32c1922-3aa9-4b16-b298-6397758f5741)
......
libvirtError: block copy still active: disk 'vdb' already in active block job