The resize operation when using the VCenter driver ends up resizing the original VM and not the newly cloned VM.
To recreate:
1) create a new VM from horizon using default debian image. I use a flavor of nano.
2) wait for it to complete and go active
3) click on resize and choose a flavor larger than what you used originally. i then usually choose a flavor of small.
4) wait for horizon to prompt you to confirm or revert the migration.
5) Switch over to vSphere Web Client. Notice two VMs for your newly created instance. One with a UUID name and the other with a UUID-orig name. "-orig" indicating the original.
6) Notice the original has be resized (cpu and mem are increased, disk is not, but that's a separate bug) and not the new clone. This is problem #1.
7) Now hit confirm in horizon. It works, but the logs contain a warning: "The attempted operation cannot be performed in the current state (Powered on).". I suspect its attempting to destroy the orig VM, but the orig was the VM resized and powered on, so it fails. This is problem #2.
Results in a leaked VM.
this looks like a regression to me