Minimal test case:

module strange_override_bug;

interface K {
	void f();
}

class A(int m) : K {
	override void f()
	in { }
	body { }
}

class B : A!(2) {
	void f() { }
}

/*
strange_override_bug.d(8): Error: variable strange_override_bug.A!(2).A.f.this override cannot be applied to variable
strange_override_bug.d(9): Error: function strange_override_bug.A!(2).A.f.__require override only applies to class member functions
*/

Compile with "in { }" line commented out!
Compiles also if i remove "override" keyword" (and it do not warn my about anything).

Was working in 2.049.