Description of problem:

Unregistered template failed to register.

Received java.lang.NullPointerException when sending:

POST /api/storagedomains/xxxxxxx-xxxx-xxxx-xxxxxx/templates/xxxxxxx-xxxx-xxxx-xxxxxx/register HTTP/1.1
Accept: application/xml
Content-type: application/xml

<action>
    <cluster id='bf5a9e9e-5b52-4b0d-aeba-4ee4493f1072'></cluster>
    <allow_partial_import>true</allow_partial_import>
</action> 

After speaking to Maor seems related to - 
https://gerrit.ovirt.org/#/c/69772/
"Once an unregistered template is being registered the updateMaxMemorySize will try to call getOsId on vmBase which is null"

Version-Release number of selected component (if applicable):
Engine - 4.1.0.4-0.1.el7
VDSM - 4.19.4-1.el7ev.x86_64

How reproducible:
100%

Steps to Reproduce:
1.Create a VM with one disk on storage domain A 
2.Make a template from the VM created in 1.
3.Detach domain A
4.Remove the domain that detached in 3 from the data center without formatting   it.
6.Import the storage domain from 4 to the data center and activate it.
7. Register the template using the command above

Actual results:
Received java.lang.NullPointerException

Expected results:
Template should register to the data center

Additional info: