Github user dkuppitz commented on the issue:
https://github.com/apache/tinkerpop/pull/714
It breaks other parts of the code when you attempt to modify the parent
traversal, in particular when you remove one or more steps. I don't remember
where the exception was thrown, but it was an IndexOutOfBoundsException. So
apparently there's a for-loop with an upper bound that is only initialized once
(which is good, I wouldn't like to recount the steps in each iteration).---
