OK, good suggestion. 
I split the `LOW_COVERAGE` into `SHIFT_LOW_COVERAGE` and `REMOVE_LOW_COVERAAGE`. They are two different jobs. 
The `REMOVE_LOW_COVERAAGE` is the original one, you can run it without shift the previous' readset.
And the `SHIFT_LOW_COVERAGE` is just shifting the ReadSet, without removing the node, so the newer LOW_COVERAGE should be `SHIFT_LOW_COVERAGE,REMOVE_LOW_COVERAGE`.

FYI @Elmira88  also.