Change to sudo: true when using Behat

Author: polothy

docs/CHANGELOG.md

@@ -10,6 +10,8 @@ The format of this change log follows the advice given at [Keep a CHANGELOG](htt
 
 ## [Unreleased]
 ### Changed
+- Recommending `sudo: true` when using Behat. See
+  [#70](https://github.com/moodlerooms/moodle-plugin-ci/issues/70) for details.
 - Updated project dependencies.  Most notably, Moodle Code Checker v2.7.1.
 
 ### Added

docs/TravisFileExplained.md

@@ -11,8 +11,9 @@ see [Travis CI's documentation](http://docs.travis-ci.com/user/getting-started/)
 # This is the language of our project.
 language: php
 
-# This tells Travis CI to use its new architecture.  Everything is better!
-sudo: false
+# If using Behat, then this should be true due to an issue with Travis CI.
+# If not using Behat, recommended to use `sudo: false` as it is faster.
+sudo: true
 
 # Installs the required version of Firefox for Behat, an updated version
 # of PostgreSQL and extra APT packages. Java 8 is only required