Remove yarn

.travis.yml

@@ -1,3 +1,8 @@
+# need sudo to remove yarn from path
+# https://docs.travis-ci.com/user/reference/overview/#Virtualisation-Environment-vs-Operating-System
+sudo: required
+dist: trusty
+
 language: python
 python: 3.6
 cache:

scripts/travis_install.sh

@@ -5,6 +5,11 @@
 set -ev
 set -o pipefail
 
+# Building should work without yarn installed globally, so uninstall the
+# global yarn that Travis installs automatically.
+sudo rm -rf $(which yarn)
+! yarn
+
 # create jupyter base dir (needed for config retrieval)
 mkdir ~/.jupyter