Cannot add full clone of a host if a template was unlinked during full clone process

Problem description: Is a template gets unlinked during the full clone process the following error is returned when attempting to save full clone configuration:

Cannot add host

Steps to reproduce:

1. Create a host and link a template to it
2. Open host configuration and press "Full clone" button
3. Open "Templates tab and unlink the template"
4. Attempt to save the clone.

Result: The above error is returned, configuration cannot be saved.
Expected: Configuration of the Full clone should be successfully saved even though the template was unlinked.

Example: