[PATCH 1 of 4 STABLE V3] lock: avoid unintentional lock acquisition at failure of readlock

[Yuya Nishihara]

On Mon, 1 May 2017 21:56:29 +0900, Yuya Nishihara wrote:
> Perhaps we can get rid of the subsequent "if locker is not None" condition,
> as a follow up.

Never mind. You're right. _testlock() has an implicit 'return None'.