5554 – [qtd] Covariance detection failure

class MA
{
}
class MB : MA
{
}
class MC : MB
{
}
class A
{ 
 MA foo() { return null; }
}
interface I
{
 MB foo();
}
class B : A
{ 
 override MC foo() { return null; }
}
class C : B, I
{ 
 override MC foo() { return null; }
}
void main()
{
}
----
Error: function test.C.foo incompatible covariant types MA() and MB()

https://github.com/D-Programming-Language/dmd/pull/746 

Commit pushed to master at https://github.com/D-Programming-Language/dmd
https://github.com/D-Programming-Language/dmd/commit/027fdbc892d7d2bd89e1d1b88accb53ca733f8de
Merge pull request #746 from yebblies/issue5554
Issue 5554 - [qtd] Covariance detection failure

Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd
https://github.com/D-Programming-Language/dmd/commit/0c46d6921050907fe413244cbe71cfa7b93135a2
fix Issue 5554 - [qtd] Covariance detection failure