Issue with 2.071: Regression or valid error?

[9il via Digitalmars-d-learn]

On Thursday, 7 April 2016 at 15:55:16 UTC, Steven Schveighoffer 
wrote:
> On 4/6/16 11:10 AM, Andre wrote:
>> [...]
>
> Just FYI, you don't need a semicolon there.
>
>>>> [...]
>
> Wow, totally agree with you. Compiler shouldn't make you jump 
> through this hoop:
>
> void foo(Cat cat)
> {
>    Animal a = cat;
>    a.create();
> }
>
> Please file a bug report, not sure why this happened.
>
> -Steve

Why this is a bug? private methods are not virtual, are they? 
--Ilya