Test case failures in proposals/29:upgrade-9/sanity.test.js

[LuqiPan]

While working on #137, I noticed that we did not set YARN_IGNORE_NODE flag in proposals/29:upgrade-9/test.sh which resulted in yarn ava not running. Setting this flag however, would result in failures in proposals/29:upgrade-9/sanity.test.js.

Fixing these test case failures are outside the scope of #137 so I'm opening an issue to document this and assigning to @turadg who based on git blame created the test file.

PS: for posterity, it would probably be helpful to set -e in proposal/29:upgrade-9/test.sh too.