length = 0 clears reserve

[Jethro via Digitalmars-d-learn]

arrays have the ability to reserve but when setting the length to 
0, it removes the reserve!! ;/

char[] buf;
buf.reserve = 1000;
buf.length = 0;
assert(buf.capacity == 0);

But I simply want to clear the buffer, not change it's 
reserve/capacity.

I've tried to hack by setting the length to 0 through a pointer, 
but that still clears the capacity!

I want to do this because I want to be able to reuse the array 
without ever reallocating(I'll set the capacity to the max that 
will ever be used, I don't have to worry about conflicts since it 
will always be ran serially).

It is a bug if dmd is setting the capacity to 0 and reallocating 
the array when the length is set to 0. It should either do it 
lazily or not at all(or, say setting the length to -1 does not 
clear the capacity, only sets the length to 0).