ExtensionIT#testSimpleSearch is flickering

java.lang.AssertionError
	at org.junit.Assert.fail(Assert.java:87)
	at org.junit.Assert.assertTrue(Assert.java:42)
	at org.junit.Assert.assertTrue(Assert.java:53)
	at org.xwiki.test.ui.extension.ExtensionIT.testSimpleSearch(ExtensionIT.java:216)

I don't understand why this test has failed:

• the screenshot shows that there are search results
• the "extension-item" class name is part of the HTML returned from the server (as proven by the HTML logged when the test failed) so findElementsWithoutWaiting should see it right way
• SimpleSearchPane#search() is waiting for the page to reload after typing the test and pressing Enter