std.container.BinaryHeap + refCounted = WTF???

[dsimcha]

I'm trying to use BinaryHeap in a multithreaded programming using
std.parallelism/parallelfuture.  I kept getting ridiculous segfaults and
stuff, and when I looked into it in a debugger, I realized the crashes had to
do with reference counting, probably caused by this line in BinaryHeap:

    private RefCounted!(Tuple!(Store, "_store", size_t, "_length"),
                       RefCountedAutoInitialize.no) _payload;

Why the heck are the payload and the length being stored in such a weird way?
 IMHO BinaryHeap shouldn't use reference counting unless Store does.  More
generally, anything that uses reference counting, especially where unexpected,
should come with a very strong warning in its ddoc so that people are aware of
the hidden caveats, like copying it using memcpy() and sharing it across threads.