new vbucket uuid not generated during tap takeover leading to potential data loss in xdcr replication

It can happen in the following scenario.

• user starts upgrading 2.5 cluster to 3.* by rebalancing in a 3.* node n1
• n1 becomes an owner of a vbucket (say 0); at this point vbucket uuid is generated for the vbucket (vbuuid0)
• another rebalance is done (addition/removal, not important) and vbucket 0 moves from n1 to another node n2 (can be both 2.5 or 3.*), n1 becomes vbucket 0 replica node
• another rebalance is done and vbucket 0 moves back to n1

After this vbucket 0 on n1 will still have vbucket uuid vbuuid0. So xdcr might incorrectly reuse previous checkpoints and not replicate data that actually needs to be replicated.