collect_all_bucket_keys() KeyError: '0'

[GertjanBrouwer]

Hi,

I am getting:

randombinaryprojectiontree.py", line 110, in bucket_keys_to_guarantee_result_set_size
    listB = self.childs[other_hash_char].collect_all_bucket_keys()
KeyError: '0'

I generated a RandomBinaryProjectionTree and added about 206 images.
I set the minimum amount to be retrieved to 2.
It gives me this error.
When I set it to 1 I don't get errors.