Description of problem: Adding a "Custom Property" to a running VM causes all the custom properties that have been previously defined to be removed (when the VM is shut down). Version-Release number of selected component (if applicable): 3.5.1 How reproducible: always Steps to Reproduce: 1. create a vm and add "sap_agent=true" custom property, start the vm 2. edit the same vm and add one more custom property (like "viodiskcache=writeback" as an example) 3. shut down the vm to have the engine apply the new property Actual results: All "Custom Properties" are deleted. Expected results: Existing "Custom Properties" are preserved and the newly defined property/ies are added. Additional info: