I am reliably observing a race condition in the MatrixAuthorizationStrategy page object when trying to add 2 users in succession

MatrixAuthorizationStrategy auth = security.useAuthorizationStrategy(MatrixAuthorizationStrategy.class);
auth.addUser("alice").admin();
auth.addUser("bob").developer();

the addition of the second user fails with :

org.openqa.selenium.TimeoutException:
Expected condition failed: waiting for alert to be present (tried for 10 second(s) with 500 milliseconds interval)

looking at a screen recoring this may be due to the fact that the tooltip for the recently added "administrator" permission for alice is showing a tooltip that is partially obscuring the button

using

• acceptance-test-harness 1.74
• selenium/standalone-firefox-debug:2.53 docker image for firefox (docker run -d -p 4444:4444 -p 5900:5900 -e no_proxy=localhost -e SCREEN_WIDTH=1680 -e SCREEN_HEIGHT=1090 selenium/standalone-firefox-debug:2.53.1)
• BROWSER=remote-webdriver-firefox