Sbt builder fix and refactor

* Fixed the issue with lost deprecation warnings. #1002148
* Refactored and removed useless indirection in the build reporter

The best would be to review the two commits separatetly. The first one fixes the issue, the last one is purely cleanup.

/cc @gkossakowski
But the common case is when the total doesn't change. So then:

* `lastWorked = 10` and `total = savedTotal = 20`
* `current = 15`

If I set workRemaining to (`20 - 5 = 5`), and then I work `15 - 5 = 5`, I just got to 100%, even though I still need 5 work units....