consumer error closing old producer stream

1) Opened a producer and made a stream request 2) Changed client to consumer with same key to producer     * the stream state becomes dead 3) As consumer attempt to close dead stream created by producer. 4) Expect SUCCESS. Got ERR_KEY_ENOENT upr stats shows the stream exists and is in dead state. and in other cases closing already dead streams has no effect other than keeping the state as dead. https://github.com/tahmmee/pyupr/blob/master/unit.py#L467