Can't instantiate SimpleTimeZone

[Andrej Mitrovic]

I was using the AE[1] library, but recently it started to fail to
compile due to essentially this:

--------
import std.datetime;

void main()
{
    Duration dur;
    auto x = new SimpleTimeZone(dur);
}
--------

> test.d(8): Error: immutable method std.datetime.SimpleTimeZone.this is not callable using a mutable object
> test.d(8): Error: no constructor for SimpleTimeZone

The only constructors available for that class are all immutable.

Why the breaking change? Did it break on purpose? And why is the error
message so awful?