Merge branch 'JENKINS-8660'

* JENKINS-8660:
  fail more gracefully if the header is not provided.
  JENKINS-8660: loading the build history cause an NPE on the History Widget

core/src/main/java/hudson/widgets/HistoryWidget.java

@@ -27,16 +27,20 @@ import hudson.Functions;
 import hudson.model.ModelObject;
 import hudson.model.Run;
 import org.kohsuke.stapler.Header;
+import org.kohsuke.stapler.HttpResponses;
 import org.kohsuke.stapler.Stapler;
 import org.kohsuke.stapler.StaplerRequest;
 import org.kohsuke.stapler.StaplerResponse;
 
 import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 
+import static javax.servlet.http.HttpServletResponse.SC_BAD_REQUEST;
+
 /**
  * Displays the history of records (normally {@link Run}s) on the side panel.
  *
@@ -151,6 +155,8 @@ public class HistoryWidget<O extends ModelObject,T> extends Widget {
     public void doAjax( StaplerRequest req, StaplerResponse rsp,
                   @Header("n") String n ) throws IOException, ServletException {
 
+        if (n==null)    throw HttpResponses.error(SC_BAD_REQUEST,new Exception("Missing the 'n' HTTP header"));
+
         rsp.setContentType("text/html;charset=UTF-8");
 
         // pick up builds to send back

core/src/main/resources/hudson/widgets/HistoryWidget/index.jelly

@@ -48,6 +48,13 @@ THE SOFTWARE.
       <tr class="build-row">
         <td colspan="3" align="right">
           <script>
+            function replace(a, b) {
+                  var p = a.parentNode;
+                  var next = a.nextSibling;
+                  p.removeChild(a);
+                  p.insertBefore(b,next);
+            }
+
             function loadAllBuildHistory() {
               // first display the "loading..." icon
               var box = $("loadAllBuildHistory");
@@ -59,14 +66,12 @@ THE SOFTWARE.
                 onComplete: function(rsp,_) {
                   <!-- neither outerHTML nor responseXML works in Firefox 2.0 -->
                   var hist = $$("buildHistory");
-                  var p = hist.parentNode;
-                  var next = hist.nextSibling;
-                  p.removeChild(hist);
 
-                  var div = document.createElement('div');
-                  div.innerHTML = rsp.responseText;
+                  var newhist = document.createElement('div');
+                  newhist.innerHTML = rsp.responseText;
+                  newhist.headers = hist.headers
 
-                  p.insertBefore(div,next);
+                  replace(hist, newhist);
                 }
             });
             }

war/src/main/webapp/scripts/hudson-behavior.js

@@ -1472,6 +1472,9 @@ function updateBuildHistory(ajaxUrl,nBuild) {
 
     function updateBuilds() {
         var bh = $('buildHistory');
+        if (bh.headers == null) {
+            // Yahoo.log("Missing headers in buildHistory element");
+        }
         new Ajax.Request(ajaxUrl, {
             requestHeaders: bh.headers,
             onSuccess: function(rsp) {