fix

msgpack/fallback.py

@@ -194,7 +194,7 @@ class Unpacker(object):
         if isinstance(next_bytes, array.array):
             next_bytes = next_bytes.tostring()
         elif isinstance(next_bytes, bytearray):
-            next_bytes = (bytes if PY3 else str)(next_bytes)
+            next_bytes = bytes(next_bytes)
         assert self._fb_feeding
         if self._fb_buf_n + len(next_bytes) > self._max_buffer_size:
             raise BufferFull