facebook/tornado — pull request #1012 by dlutxx (2014-03-10 10:32:03+00:00)
Title: remove useless code of BaseIOStream

Just found a line of duplication in BaseIOStream in iostream.py, [line 206](https://github.com/facebook/tornado/blob/master/tornado/iostream.py#L206).

It re-assigns value to `self._stream_callback`, which is already done in [line 198](https://github.com/facebook/tornado/blob/master/tornado/iostream.py#L198).