fixup! fixup! fixup! fixup! fixup! fixup! fixup! fixup! fixup! fixup! Fix Travis when SIX_VERSION isn't specificed

Author: gsnedders

requirements-install.sh

@@ -5,7 +5,7 @@ if [[ $USE_OPTIONAL != "true" && $USE_OPTIONAL != "false" ]]; then
   exit 1
 fi
 
-pip install -U setuptools pip==6.0.7
+pip install pip==6.1.0
 
 pip install -U -r requirements-test.txt