A routine has a postcondition with an `old' expression which involves
a function call.  An exception is raised during execution of this
function.  If the system is frozen, the recipient of the exception is
not the routine containing the `old' expression, but that routine's
caller.  If the system is melted, the routine containing the `old'
expression is the recipient of the exception.

Discovered in Release 3.2.4.