CA-101175: Replace Event.next by Event.from

Signed-off-by: Vincent Bernardoff <vincent.bernardoff@citrix.com>
Merge pull request #1236 from vbmithr/CA-101175

CA-101175: Replace Event.next by Event.from
Revert fix for CA-101238

The duplicate MAC seed check breaks cross-pool migration of VMs with
snapshots, since snapshots will usually have the same MAC seed as the VM
they belong to.

Signed-off-by: John Else <john.else@citrix.com>
Merge pull request #1242 from johnelse/revert-ca-101238

Revert fix for CA-101238