Where are we on getting rid of Nullable's alias this? Was that happening?

[aliak]

Just ran in to this awesome bug

import std;

struct Foo {
     Nullable!string a;
}

void main() {
     string a;
     auto app = appender(&a);
     formattedWrite(app, "%s", Foo());
}

Because this: 
https://github.com/dlang/phobos/blob/master/std/format.d#L3448

Because "StringTypeOf!(Nullable!string) = Nullable!string()" 
calls get implicitly, which assers :/

I'm not sure if there's a workaround. I remember there was talk 
of removing alias this in Nullable? But I also remember there was 
no consensus?

Cheers,
- Ali