Wait till we reach hub after setting root password

Lately anaconda can take up to 10 seconds to exit the root pw
spoke, which can defeat the subsequent `wait_still_screen` that's
meant to wait out the 'slide-in-from-the-top' animation of the
hub. So let's assert the hub after we click Done, then the still
screen wait will only happen *once the hub is visible* and should
really do its job.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

tests/_do_install_and_reboot.pm

@@ -35,6 +35,8 @@ sub _set_root_password {
             # differs; pre-release text is also translated)
         }
         assert_and_click "anaconda_spoke_done";
+        # exiting this screen can take a while, so check for the hub
+        assert_screen "anaconda_main_hub";
     }
 }