The different behavior of is() from bug 7868 depending on whether it was invoked from a static if condition or not might be acceptable, but this example is clearly a regression in my eyes:

---
module a;

struct A {
  import b : c;

  // Instantiate template which uses derivedMembers.
  alias D!A Test;

  // Unrelated template from other module - »not defined«.
  static if (c!()()) {}
}

// Just something using derivedMembers.
template D(T) {
  mixin({
    foreach (name; __traits(derivedMembers, T)) {}
    return "";
  }());
}
---
---
module b;
bool c()() { return true; }
---

It compiled fine in DMD 2.058, but fails with »template instance c!() template 'c' is not defined, did you mean a?« in latest Git master (7c22b8a), which is absolutely not related to the cause of the error.