Description of problem:

Trying to set the Initialization of a VM to an empty value via REST api does not work.

Version-Release number of selected component (if applicable):
rhevm-4.1.5.2-0.1.el7.noarch

How reproducible:
100%

Steps to Reproduce:

Doing a PUT of an empty initialization does not work. All the configurations remain.

DEBUG:root:PUT /ovirt-engine/api/vms/b595e7fd-21e9-4bd7-ac5b-8559a78912b9 HTTP/1.1
DEBUG:root:Content-Length: 31
DEBUG:root:<vm>
DEBUG:root:  <initialization/>
DEBUG:root:</vm>
DEBUG:root:HTTP/1.1 200 OK

If I try just the Cloud init part, no changes as well

Everything is still there:

DEBUG:root:    <initialization>
DEBUG:root:        <configuration>
                   .....
DEBUG:root:        </configuration>
DEBUG:root:        <host_name>thisisatest</host_name>
DEBUG:root:        <nic_configurations/>
DEBUG:root:        <regenerate_ssh_keys>false</regenerate_ssh_keys>
DEBUG:root:    </initialization>

I'm using this:

vms_service = connection.system_service().vms_service()

for vm in vms_service.list():
    if vm.name.startswith("germano-"):
        print "Updating %s" % vm.name
        vm_service = vms_service.vm_service(vm.id)
        vm_service.update(
            types.Vm(
                initialization=types.Initialization(
                )
            )
        )

And the cloud_init element inside initialization seems to suffer from the same problem.

Actual results:
Initialization still there

Expected results:
Initialization removed