fix deleting source_iter
Summary: (https://github.com/pytorch/fairseq/commit/e171c8d86a939cf4ebc483cd649bee1935379771) removed this iterator, so we need to remove this line otherwise jobs will fail. I guess we never ran into this during testing since we never actually finished an entire epoch and consumed everything since we call `take`
@@ -488,8 +488,6 @@ class BackgroundConsumer(Thread):
except Exception as e:
self._queue.put(e)
- del self._source_iter
-
class BufferedIterator(object):
def __init__(self, size, iterable):
