This PR now also includes a fix to the problem of mult-routines building blocks on the same input. This PR works as before with regards to stopping the work, but it just will not spin up a second routine if one is already building. So if the CL does N calls to FCU+buildblock, and N calls to GetPayload, only the first of each will do something, the other calls will be mostly no-ops.

This PR also adds printout of the payload id into the logs.