The --use-known-results switch simulates sampling (with fault
expansion, FESamplingPruner) by reusing results from a previous
campaign covering the full fault space (that used the "basic" pruner).
The pruner only creates entries in the "fspgroup" table that refer to
already existing pilots and corresponding results.
This switch is not for normal Fail* use, but only for experimenting
with the FESamplingPruner.
Change-Id: I1bf561d93f55918d243c5306551a1c6b48027198
a1e3b31cd5