Why rule construct "object instanceof expression" can't be jitted?

Issue

Following expression:

rule "RG_TEST_1"
when
    $event: OtherDummyEvent ()
    Object(this instanceof $event.clazz) //this expression
then
     insert(new String('ok'));
end

can't be jitted. Following WARN message is logged during compilation:

"2015-12-16 16:39:54,432 (drools-worker-1) [WARN - org.drools.core.rule.constraint.MvelConstraint.executeJitting(MvelConstraint.java:329)] Exception jitting: this instanceof $event.clazz This is NOT an error and NOT prevent the correct execution since the constraint will be evaluated in intrepreted mode"