Description of problem:
When VM uses an existing populated PVC, DV's export manifest can't be applied.

Version-Release number of selected component (if applicable):
4.14

How reproducible:
Always

Steps to Reproduce:

1. Create a DV/PVC on CSI storage (it will use populators)

$ virtctl image-upload dv cirros-dv --image-path=./cirros-0.4.0-x86_64-disk.qcow2 --size=1Gi --storage-class=ocs-storagecluster-ceph-rbd --insecure

2. Create a VM that will use this PVC

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
name: vm-from-uploaded-dv
spec:
running: true
template:
spec:
domain:
devices:
disks:

• disk:
  bus: virtio
  name: pvc-edd0ce9a-2c84-46b3-bc42-7450c2f8602b
  rng: {}
  resources:
  requests:
  memory: 100Mi
  volumes:
• name: pvc-edd0ce9a-2c84-46b3-bc42-7450c2f8602b
  persistentVolumeClaim:
  claimName: cirros-dv

3. Create a VMExport and save manifests

$ virtctl vmexport download export --manifest --vm=vm-from-uploaded-dv --include-secret --output=manifest.yaml

4. Add/replace the 'namespace: target' in the manifest.yaml

5. Try to create a target VM:

$ oc create -f manifest.yaml
configmap/export-ca-cm-export created
virtualmachine.kubevirt.io/vm-from-uploaded-dv created
secret/header-secret-export created
Error from server: error when creating "manifest.yaml": admission webhook "datavolume-validate.cdi.kubevirt.io" denied the request: External population is incompatible with Source and SourceRef DataSourceRef and DataSource must match

6. DataVolume from manifest.yaml:

—
apiVersion: cdi.kubevirt.io/v1beta1
kind: DataVolume
metadata:
creationTimestamp: null
name: cirros-dv
namespace: target
spec:
pvc:
accessModes:

• ReadWriteMany
  dataSource:
  apiGroup: cdi.kubevirt.io
  kind: VolumeUploadSource
  name: volume-upload-source-aa30e962-d15e-4a5f-a88d-95e1989c6fbd
  dataSourceRef:
  apiGroup: cdi.kubevirt.io
  kind: VolumeUploadSource
  name: volume-upload-source-aa30e962-d15e-4a5f-a88d-95e1989c6fbd
  resources:
  requests:
  storage: "1073741824"
  volumeMode: Block
  source:
  http:
  certConfigMap: export-ca-cm-export
  secretExtraHeaders:
• header-secret-export
  url: https://virt-exportproxy-openshift-cnv.<mypath>/api/export.kubevirt.io/v1alpha1/namespaces/default/virtualmachineexports/export/volumes/cirros-dv/disk.img.gz
  status: {}
  —

Actual results:
Error from server: error when creating "manifest.yaml": admission webhook "datavolume-validate.cdi.kubevirt.io" denied the request: External population is incompatible with Source and SourceRef DataSourceRef and DataSource must match

Expected results:
VM and DV/PVC were created successfully in the target namespace/cluster

Additional info:
When VM uses dataVolumeTemplates - we don't hit this issue and it works fine.