ArrayBoundsError for associative array operation

[Frits van Bommel]

xs0 wrote:
> Yes, I think it's a bug.. The reason it happens is the following:
> 
> 1) all the nodes happen to fall into the same bucket in the AA
> 2) when that is the case, entries get placed into a binary tree
> 3) the ordering in the binary tree is determined by hashcodes first, 
> opCmp second (in this case, opCmp can be ignored, as it isn't called at 
> all)
> 4) after that node is deleted, the tree looks like this:
>      root.hash        =  315901071
>      root->right.hash = 2716102924
> 5) and, finally, the bug: in aaA.d around line 319, the following takes 
> place:
> 
>      c = key_hash - e.hash;
>      // snip
>      if (c < 0)
>          e = e.left;
>      else
>          e = e.right;
> 
>    because those two hash values are too far apart, c becomes negative 
> (-1894765443) and the left subtree is followed instead of the right 
> subtree, causing the key to not be found.

Well, at least the fix is easy. Comparing the hashes directly should 
solve the problem.