address comments

Author: davies

python/pyspark/worker.py

@@ -74,7 +74,7 @@ def main(infile, outfile):
                 _broadcastRegistry[bid] = Broadcast(bid, value)
             else:
                 bid = - bid - 1
-                _broadcastRegistry.pop(bid, None)
+                _broadcastRegistry.remove(bid)
 
         _accumulatorRegistry.clear()
         command = pickleSer._read_with_length(infile)