Test failure.

https://ci.jenkins-ci.org/job/jenkins_main_trunk/1943/testReport/junit/org.jvnet.hudson.test/JellyTestSuiteBuilder$JellyCheck/lib_layout_progressiveRendering_jelly/

core/src/main/resources/lib/layout/progressiveRendering.jelly

@@ -21,6 +21,7 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 -->
+<?jelly escape-by-default="true"?>
 <j:jelly xmlns:j="jelly:core" xmlns:st="jelly:stapler" xmlns:d="jelly:define" xmlns:l="/lib/layout" xmlns:t="/lib/hudson" xmlns:f="/lib/form" xmlns:x="jelly:xml">
     <st:documentation>
         <st:attribute name="handler" use="required">