Mutate, Prepare -> auto delete failure

The following sequence of events will trigger DCP errors

1. seqno:1 mutate(k1) -> replicate over DCP
2. seqno:2 prepare(k1) -> replicate over DCP
3. ephemeral auto delete triggers

The first two events will leave a committed k1 and prepare k1 in the active hash-table. When auto delete triggers it will use the hash-table visitor. The hash-table visitor will see all of the items, ignoring the prepare but will see the committed item at seqno 1, this is candidate for deletion.

DCP effectively sends

1. seqno:1 mutate(k1)
2. seqno:2 prepare(k1)
3. seqno:3 delete(k1) ... a delete of seqno:1

At this point seqno:3 triggers an error and disconnects DCP.