Explicity install six to unbreak Travis.
set -e
source "${HOME}/INSTALL/bin/activate"
-pip install --upgrade pip wheel setuptools
+pip install --upgrade pip wheel six
+pip install --upgrade setuptools
pip install nodeenv
# Install the latest version of nodejs. Some packages
# may not be compatible with the version.
-nodeenv -p --prebuilt
+# nodeenv -p --prebuilt
# This is a temporary hack to un-break the Travis
# build.
