fails:Enumerable#slice_when when given a block splits chunks between adjacent elements i and j where the block returns true
fails:Enumerable#slice_when when given a block calls the block for length of the receiver enumerable minus one times
fails:Enumerable#slice_when when an iterator method yields more than one value processes all yielded values
fails:Enumerable#slice_when when given a block doesn't yield an empty array on a small enumerable
