`test_cod_widget` not the most reliable test

Working on #647, I updated the main commit with a comment. All of a sudden, `test_cod_widget` was failing. I re-ran the failed test, only for it to fail again. @danielhollas re-ran it later - passed! Not reliable. @danielhollas note that I can't figure out how to paste the failure here, since your successful re-running of the test appears to have overwritten the failure. If you're aware of a way to recover it, please add it here.