Const ref queue as function argument

Hello, Under Incisive 10.2 I am passing a queue into a function with the qualifier "const ref". I understand that this qualifier should prevent the function from modifying the queue, that doesn't seem to be true. Is my understanding correct? Here is sample code illustrating the point:

class TestClass ;

function unPack (const ref bit[7:0] bytes[$]) ;
$display(bytes.size());
bytes.pop_back();
$display(bytes.size());
endfunction : unPack

endclass : TestClass


In an program block:

TestClass tc;

tc = new();
bytes = {1,2,3};
$display("before");
$display(bytes.size());
tc.unPack(bytes);
$display("after");
$display(bytes.size());


The simulator output is:

before
3
3
2
after
2

This indicates that the queue is being modified in the unPack function even though it is being passed in as "const ref". Is this behavior expected? Thanks