Fix IPv6 in Travis

.travis.yml

@@ -3,4 +3,9 @@ sudo: false
 node_js:
   - "node"
 before_script:
+  # Add an IPv6 config - see the corresponding Travis issue
+  # https://github.com/travis-ci/travis-ci/issues/8361
+  - if [ "${TRAVIS_OS_NAME}" == "linux" ]; then
+      sudo sh -c 'echo 0 > /proc/sys/net/ipv6/conf/all/disable_ipv6';
+    fi
   - export DISPLAY=:99.0; sh -e /etc/init.d/xvfb start