From with modify fires unexpected rule

Issue

The rules below expect that only "R1" is fired when Person ("John", 20) is inserted. However, "R2" is also fired though age is set to 5 in modify block.

rule "R1"
    salience 1
    when
        $p : Person()
        Person( age > 10 ) from $p 
    then
        modify ($p) {
          setAge(5);
        }
        System.out.println( "R1, " + $p);
end

rule "R2"
    salience 0
    when
        $p : Person()
        Person( age > 10 ) from $p 
    then
        System.out.println( "R2, " + $p);
end