[PATCH 4 of 7] dirstate: centralize _cwd handling into _cwd method

[Yuya Nishihara]

On Mon, 03 Jul 2017 02:53:18 +0900, FUJIWARA Katsunori wrote:
> # HG changeset patch
> # User FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
> # Date 1499017960 -32400
> #      Mon Jul 03 02:52:40 2017 +0900
> # Node ID ce3d2f9b19ec075671ba185bb77cde064c049b27
> # Parent  8e03783672a372061aa6567e370fc28c5b7bda3b
> dirstate: centralize _cwd handling into _cwd method

Queued up to here, thanks.