Immutable array initialization in shared static this

[Tommi]

The following code doesn't compile. It seems like a compiler bug 
to me, but I can't find a bug report about it. Is it a bug?

private immutable(int[]) constants;
shared static this()
{
    constants.length = 10;
    constants[0] = 123; // Error: constants[0] isn't mutable
}