No errors for non-virtual NewSlot members overrides

[auduchinok]

public class A
{
    public virtual void M1() { }
    public virtual void M2() { }
    public virtual void M3() { }
    public virtual void M4() { }
}

public class B : A
{
    public override void M1() { }
    public void M2() { }
    public new void M3() { }
    public new virtual void M4() { }
}

type C() =
    inherit B()

    override this.M1() = ()
    override this.M2() = () // error is expected
    override this.M3() = () // error is expected
    override this.M4() = ()

[TIHan]

I don't know if this is a regression or not. But it should error as you say. More importantly, it shows where we have a test gap.

Thank you for reporting this.