null Rebindable

[bearophile]

This D2 program shows that you can't test if a class reference wrapped with 
Rebindable is null:


import std.typecons;
const class Foo {}
void main() {
    auto a = Rebindable!Foo(new Foo);
    a = new Foo;
    assert(a !is null); // err
}


DMD 2.050 generates:
test.d(6): Error: incompatible types for ((a) !is (null)): 
'Rebindable!(const(Foo))' and 'void*'


Is this the currently correct way to do it? (It works):

assert(a.get() !is null); // OK

I have seen the get() method is not documented on the site, so is that a 
temporary limitation caused by the unfinished "alis this" implementation?

Bye and thank you,
bearophile