MDL-70726 behat: should_not_exist function does not work correctly

lib/tests/behat/behat_general.php

@@ -1000,7 +1000,7 @@ EOF;
             // Using the spin method as we want a reduced timeout but there is no need for a 0.1 seconds interval
             // because in the optimistic case we will timeout.
             // If all goes good it will throw an ElementNotFoundExceptionn that we will catch.
-            return $this->find($selectortype, $element, $exception, false, behat_base::get_reduced_timeout());
+            $this->find($selectortype, $element, $exception, false, behat_base::get_reduced_timeout());
         } catch (ElementNotFoundException $e) {
             // We expect the element to not be found.
             return;