Clash between functions that shouldn't be in the same partial ordering set

[TommiT]

I'm pretty sure the following is a compiler bug, right? (using 
DMD 2.063)

---------
module a;

void foo(char)
{
}

---------
module b;

enum MyEnum : int { _ }

void foo(MyEnum)
{
}

---------
module main;

import a;
import b;

void main()
{
     foo(char.init);
     foo(MyEnum.init); // [1]
}

// 1) Error: b.foo at b.d(5) conflicts with a.foo at a.d(3)

There shouldn't be a problem with this cross-module overloading, 
because MyEnum isn't implicitly convertible to char and vice 
versa, and thus the partial ordering of functions should consider 
a.foo and b.foo unordered.