Description of problem:
Can't hotplug virtio-scsi disk to rhel8 q35 guest which the bootable disk is virtio-scsi disk

Version-Release number of selected component (if applicable):
RHV server:
rhvm-4.3.3.7-0.1.el7.noarch

RHV host:
vdsm-4.30.15-1.el7ev.x86_64
qemu-kvm-rhev-2.12.0-28.el7.x86_64
libvirt-4.5.0-17.el7.x86_64
kernel-3.10.0-1048.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Create and start a vm with a virtio-scsi bootable disk.
2. Click 'System' and then select 'Disks' label, click 'New' to create a new virtual disk.
3. In the pop-up sub-webpage in step2, fill in legal values for 'Size(GB)' and 'Alias' parameters, such as create a 1G named 'test' virtual disk, and then click 'OK'.
4. Select the VM and click the 'Disks' option of VM, click 'Attach', select 'test' virtual disk with 'virtio-scsi' interface, then click 'OK'.

Actual results:
Can't hotplug successfully with error: Failed to plug a disk
Events:
VDSM intel_2 command HotPlugDiskVDS failed: Requested operation is not valid: Domain already contains a disk with that address

Expected results:
Can hotplug disk successfully

Additional info:
engine.log
2019-05-30 00:41:35,693-04 ERROR [org.ovirt.engine.core.bll.storage.disk.HotPlugDiskToVmCommand] (EE-ManagedThreadFactory-engineScheduled-Thread-38) [2938af8d] Command 'org.ovirt.engine.core.bll.storage.disk.HotPlugDiskToVmCommand' failed: EngineException: org.ovirt.engine.core.vdsbroker.vdsbroker.VDSErrorException: VDSGenericException: VDSErrorException: Failed to HotPlugDiskVDS, error = Requested operation is not valid: Domain already contains a disk with that address, code = 45 (Failed with error FailedToPlugDisk and code 45)
2019-05-30 00:41:35,696-04 INFO  [org.ovirt.engine.core.bll.storage.disk.HotPlugDiskToVmCommand] (EE-ManagedThreadFactory-engineScheduled-Thread-38) [2938af8d] Lock freed to object 'EngineLock:{exclusiveLocks='[c561b2bb-ade5-451f-a163-fe8d7d18d1f9=DISK]', sharedLocks='[adbfc0f6-554f-45ec-9167-ec4662ab8b2a=VM]'}'
2019-05-30 00:41:35,729-04 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (EE-ManagedThreadFactory-engineScheduled-Thread-38) [2938af8d] EVENT_ID: USER_FAILED_HOTPLUG_DISK(2,001), Failed to plug disk jiyan_80_Disk1 to VM jiyan_80 (User: admin@internal-authz).