This is documented behaviour.

In most cases a "bug" like this is a sign the idea behind your hash tree is wrong. Use the hierarchy of the hash tree to your advantage or just make it a single hash.
--
Jaap Karssenberg || Pardus (Larus)? <pardus@cpan.org>
>>>> Zoidberg: So many memories, so many strange fluids gushing out of patients' bodies.... <<<<