Description of problem:

Usability and UX issue. This does not break any functionality.

When the Edit VM dialog is dismissed using the OK button two backend commands are called:

UpdateVmCommand and UpdateVmDiskCommand

We only allow editing some fields for the hosted engine VM and check for it in the UpdateVmCommand. But the user always gets an error from the UpdateVmDisk command because it specifically disallows changes to hosted engine VM's disks.

This would be fine if the user actually attempted to change something in the disk area. But the error is displayed even when no disk change is requested.

Version-Release number of selected component (if applicable):

master branch, but probably 3.6 too

How reproducible:

Always

Steps to Reproduce:
1. Use hosted engine VM or change the origin type of some arbitrary VM to 6 (MANAGED_HOSTED_ENGINE)
2. Edit VM (pre 3.6.3, or ask for my patches)
3. Observe the error

Actual results:

Disk update command is always called and always shows the error message.

Expected results:

Disk update should only be executed when a change is detected.