This is an optimization when increment 0. But it introduced some new problems.
1.As the TODO said, Does zero value mean reset ttl?
HBASE-17318 have to introduce a new variable "firstWrite" because it don't apply 0.
3. There is a coprocessor method postMutationBeforeWAL to return a new cell. But it may be not applied.
So my proposal is remove this optimization. Any suggestions are welcomed.