Weird interaction with public and non-public imports

[SealabJaster]

Please see: https://run.dlang.io/is/2mwcPH

I'd expect that the `isInstanceOf` would be true instead of false 
here.

Commenting out the public import changes the output of 
`fullyQualifiedName`. I can kind of see why this happens, but 
it's kind of annoying when things like `isInstanceOf` silently 
fail due to this.

For context: I found this after getting a compiler error after 
stitching a bunch of D files together, which is why there's a mix 
of a public import and local import in the same file.

Part of me feels like it's a bug since if the alias `T` is using 
one "version" (for lack of a better word) of `Nullable`, then 
surely that same "version" would be given to `isInstanceOf`?

It can get a bit more interesting as well: 
https://run.dlang.io/is/n5jzJs