regression test is running, but these is a epoch mismatch fatal

@hongchao, can you check the why there is epoch mismatch error? the regression test seems to be working with each iteration comes back right value.
If you check your own test:
https://github.com/go-distributed/meritop/blob/master/tree_topo_test.go#L62

When you say number = 8, it means 0 -- 8:
https://github.com/go-distributed/meritop/blob/master/tree_topo_test.go#L36