512 – Assigning to constants in a forwarded constructor doesn't work

Under the "Const Attribute" section, the spec contains code like the following:
class C {
	const int a;
	const int b;
	this() {
		a = 3;
		b = 2;
	}
	this(int x)
	{
		this();		// ok, forwarding constructor
	}
}
However, this code does not compile, producing errors:
asdf.d(11): constructor asdf.C.this missing initializer for const field a
asdf.d(11): constructor asdf.C.this missing initializer for const field b
It seems to me that there's no particular reason why this shouldn't work, so I'm tagging this as "rejects-valid" as well as "spec".

789 is a duplicate of this bug, but as it's the one that's been marked fixed I'll mark this as the duplicate.
*** This bug has been marked as a duplicate of 789 ***