only in patch2:
unchanged:
--- a/tests/src/FunctionalJavascript/SiteAlertCacheWorkaroundTest.php
+++ b/tests/src/FunctionalJavascript/SiteAlertCacheWorkaroundTest.php
@@ -60,8 +60,10 @@ class SiteAlertCacheWorkaroundTest extends SiteAlertWebDriverTestBase {
     // responsible for refreshing the alerts should be loaded in the page.
     $this->assertJavaScriptPresent();
 
-    // Refresh the page for a few seconds until the alert appears. Thanks to the
+    // Ensure enough time has passed and reload the page. Thanks to the
     // workaround this will work regardless of the fact that the page is cached.
+    sleep(2);
+    $this->drupalGet('<front>');
     $this->assertSiteAlertAppears('Scheduled alert');
 
     // Disable the alert. Now there are no more scheduled alerts, so the