Inconsistent behaviour static assert directly or via mixin?

[DLearner via Digitalmars-d-learn]

Consider:
```
void main() {

   string Foo() {
      if (__ctfe) {

         return `static assert(false, "Indirect");`;
      } else {
         return ``;
      }
   }

//   static assert(false, "Direct");

   mixin(Foo());
}

```
If run, produces 'Indirect' message _and nothing else_.

Now remove the '//', get 'Direct' message _and code dump_.

Inconsistent behaviour?