From 908ccdc93722fa931e8b1063d981247fdd3be642 Mon Sep 17 00:00:00 2001
From: Kang Ren <kangren.chia@gmail.com>
Date: Thu, 19 Oct 2017 04:25:32 +0000
Subject: [PATCH] add autoservernum option

---
 imgkit/imgkit.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/imgkit/imgkit.py b/imgkit/imgkit.py
index 9cc1bfc..1d16da9 100644
--- a/imgkit/imgkit.py
+++ b/imgkit/imgkit.py
@@ -82,6 +82,9 @@ def _command(self, path=None):
         if '--xvfb' in options:
             options.remove('--xvfb')
             yield self.xvfb
+            # auto servernum option to prevent failure on concurrent runs
+            # https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/348052
+            yield '-a'
 
         yield self.wkhtmltoimage