[FIXED JENKINS-24316] Fixed unknown task icon src path construction

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

@@ -113,7 +113,10 @@ THE SOFTWARE.
         <j:set var="iconMetadata" value="${icons.getIconByUrl(attrs.icon)}"/>
       </j:if>
 
-      <j:set var="icon" value="${rootURL}${icon.startsWith('images/') || icon.startsWith('plugin/') ? h.resourcePath : ''}/${icon}"/>
+      <j:if test="${!icon.startsWith('/')}">
+        <j:set var="icon" value="/${icon}"/>
+      </j:if>
+      <j:set var="icon" value="${rootURL}${icon.startsWith('images/') || icon.startsWith('plugin/') ? h.resourcePath : ''}${icon}"/>
       <j:when test="${enabled==false}">
         <div class="task disabled">
           <span>

test/src/test/java/lib/layout/IconTest.java

@@ -62,6 +62,9 @@ public class IconTest extends HudsonTestCase  {
         // class specs not in "normal" order...
         assertIconToImageOkay(icons.get(4), "/images/16x16/aborted.png");
         assertIconToImageOkay(icons.get(5), "/images/24x24/aborted.png");
+
+        // src attribute...
+        assertIconToImageOkay(icons.get(6), "/plugin/xxx/icon.png");
     }
 
     public void testBallColorTd() throws Exception {
@@ -89,6 +92,9 @@ public class IconTest extends HudsonTestCase  {
         assertIconToImageOkay(taskDivs.get(2).getElementsByTagName("img").get(0), "/images/16x16/blue.png", "icon-blue icon-sm");
         assertIconToImageOkay(taskDivs.get(3).getElementsByTagName("img").get(0), "/images/16x16/blue.png", "icon-blue icon-sm");
         assertIconToImageOkay(taskDivs.get(4).getElementsByTagName("img").get(0), "/images/16x16/blue.png", "icon-blue icon-sm");
+
+        assertIconToImageOkay(taskDivs.get(5).getElementsByTagName("img").get(0), "/plugin/xxx/icon.png");
+        assertIconToImageOkay(taskDivs.get(6).getElementsByTagName("img").get(0), "/plugin/xxx/icon.png");
     }
 
     public BallColor getBallColorAborted() {

test/src/test/resources/lib/layout/IconTest/01_testIcons.jelly

@@ -37,6 +37,11 @@ THE SOFTWARE.
       -->
       <l:icon class="icon-sm icon-aborted " />
       <l:icon class="icon-md icon-aborted" />
+
+      <!--
+      src attribute...
+      -->
+      <l:icon src="/plugin/xxx/icon.png" />
     </div>
   </l:main-panel>
 </l:layout>

test/src/test/resources/lib/layout/IconTest/03_testTask.jelly

@@ -35,6 +35,10 @@ THE SOFTWARE.
       <l:task href=".." icon="16x16/blue.gif" title="Title"/>
       <l:task href=".." icon="images/16x16/blue.gif" title="Title"/>
       <l:task href=".." icon="/images/16x16/blue.gif" title="Title"/>
+
+      <!-- unknown icon urls... -->
+      <l:task href=".." icon="/plugin/xxx/icon.png" title="Title"/>
+      <l:task href=".." icon="plugin/xxx/icon.png" title="Title"/>
     </l:tasks>
 
   </l:main-panel>