From 09476d8efaba7501908981bedb3f78dafafd5909 Mon Sep 17 00:00:00 2001
From: yuvipanda <yuvipanda@gmail.com>
Date: Sun, 30 Jul 2017 02:21:45 -0700
Subject: [PATCH] Fix tarfile mode parameter that doesn't work in 3.4

---
 repo2docker/detectors.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/repo2docker/detectors.py b/repo2docker/detectors.py
index effbeddd..1ccbc0ab 100644
--- a/repo2docker/detectors.py
+++ b/repo2docker/detectors.py
@@ -352,7 +352,7 @@ class BuildPack(LoggingConfigurable):
 
     def build(self, image_spec):
         tarf = io.BytesIO()
-        tar = tarfile.open(fileobj=tarf, mode='x')
+        tar = tarfile.open(fileobj=tarf, mode='w')
         dockerfile_tarinfo = tarfile.TarInfo("Dockerfile")
         dockerfile = self.render().encode('utf-8')
         dockerfile_tarinfo.size = len(dockerfile)