Bugfix: Fix problems exposed by unit tests in f_status.

Bugfix: Fix problems exposed by unit tests in f_status.

The signal bit can be confused with the error and warning bits.
The tests for checking if the signal bit is set need to test exclusively for the signal bit being set.
The tests for the error and warning bits do not care if this is a signal.
This is done to simplify some of the logic.
In the cases where the signal bit is to be tested, first check the signal bit and then check for the othr bits.