Fix read_in_chunks on Python 3.7
According to this will
stop working in Python 3.7: fix it now.
Closes
@@ -83,7 +83,7 @@ def read_in_chunks(iterator, chunk_size=None, fill_size=False,
if empty and yield_empty:
yield b('')
- raise StopIteration
+ return
if fill_size:
if empty or len(data) >= chunk_size:
