A class inherits a deferred feature from one class and an effective
feature of the same name from another class.  Both features have a
precondition and a postcondition.  The flatshort form of the heir
class looks as expected, with all alternative preconditions present.
But when the system is executed, the precondition and postcondition of
the deferred precursor feature are not monitored.

Discovered in Release 3.2.3b.