[PATCH 1 of 1 4test] util: check if re2 works before using it (issue 3964)

[Matt Mackall]

On Mon, 2013-07-01 at 06:52 +0200, Simon Heimberg wrote:
> # HG changeset patch
> # User Simon Heimberg <simohe at besonet.ch>
> # Date 1372654258 -7200
> # Node ID 9c97c44192062eea19b956c5d9697a4790ceee2b
> # Parent  77440de177f799f9f3bd6236c5b45fb8e15687e7
> util: check if re2 works before using it (issue 3964)

Manually tested and queued for default, thanks.

-- 
Mathematics is the supreme nostalgia of our time.