Description of problem:
When you request a migration of VM, it is possible to designate VM's current host as a target host. In that case, migration will fail very uninformative error message:

Server [EVM] VM [test-migra-zrmu] Step [CheckMigration] Status [Error Migrating VM] Message [Migrating VM]

Version-Release number of selected component (if applicable):
CFME 5.9.2.3
RHV 4.2.3

How reproducible:
100 %

Steps to Reproduce:
1. Have a CFME appliance with RHV provider that has two hosts. Have a VM on one host. In my case the env looked like this:
-VM "test-migra-zrmu" on "host_mixed_2"
-one host called "host_mixed_1"
-another host called "host_mixed_2"
2. Go to the VM's detail page and request migration of the VM (Lifecycle -> Migrate this VM). When asked about target host, supply the host the the VM currently resides on.
3. Submit the form and monitor the migration request.

Actual results:
Form can be submitted in that way and the request will fail with uninformative error message.

Expected results:
In ideal case, I would expect that CFME won't allow me to migrate VM to its current host. If it does, I would at least expect some more descriptive error message.

Additional info:
In RHV 4.2.3, when requesting migration of a VM, you cannot choose its current host as a migration target.