[PATCH STABLE] tests: fix test-patch.t on pickier /bin/sh implementations

[Yuya Nishihara]

On Tue, 12 Jun 2018 18:20:39 -0400, Augie Fackler wrote:
> # HG changeset patch
> # User Augie Fackler <augie at google.com>
> # Date 1526871918 14400
> #      Sun May 20 23:05:18 2018 -0400
> # Branch stable
> # Node ID 0c4019611293212012b598949832dcb2de6b96b2
> # Parent  3c84493556db3bffcff2fa2f24bb6738dde9fc58
> tests: fix test-patch.t on pickier /bin/sh implementations

Queued for stable, thanks.