Build docs target with sudo: false to magically fix it

.travis.yml

@@ -14,8 +14,7 @@ matrix:
 # only build docs on linux
     - os: linux
       dist: trusty
-      sudo: required
-      compiler: gcc
+      sudo: false
       env: CODE_BUILD=0 LINUX_BUILD=0 APPLE_BUILD=0 DOCS_BUILD=1
     - os: linux
       dist: trusty

scripts/travis/docs_compile.sh

@@ -1,2 +1,2 @@
 #!/bin/sh
-#cd docs/ && make html
+cd docs/ && make html

scripts/travis/docs_setup.sh

@@ -1,3 +1,3 @@
 #!//bin/sh
-sudo pip install --upgrade pip setuptools
-sudo pip install Sphinx sphinx-rtd-theme
+pip install --upgrade pip setuptools
+pip install Sphinx sphinx-rtd-theme