Rules using bound variables for properties in constraints are evaluated in class reactivity

Issue

Rules using bound variables for properties in constraints are evaluated in class reactivity even though property reactivity is expected by default.
Here is an example rule which has a problem.

rule "rule-1"
  when
    $fact: Fact( $property: a, $property == 50 )
  then
    System.out.println("***** Action of rule-1");
    modify($fact) {
      setResult("OK")
    }
end

With this example rule, the rule "rule-1" is executed infinitely when the condition of the fact matches.

This does not happen with RHDM 7.3.1 and before. (i.e. it works in Property Reactivity.)