added a tag to override the currentDescriptorByNameUrl

core/src/main/java/hudson/Functions.java

@@ -1317,4 +1317,19 @@ public class Functions {
     public static String createRenderOnDemandProxy(JellyContext context, String attributesToCapture) {
         return Stapler.getCurrentRequest().createJavaScriptProxy(new RenderOnDemandClosure(context,attributesToCapture));
     }
+
+    public static String getCurrentDescriptorByNameUrl() {
+        return Descriptor.getCurrentDescriptorByNameUrl();
+    }
+    
+    public static String setCurrentDescriptorByNameUrl(String value) {
+        String o = getCurrentDescriptorByNameUrl();
+        Stapler.getCurrentRequest().setAttribute("currentDescriptorByNameUrl", value);
+
+        return o;
+    }
+
+    public static void restoreCurrentDescriptorByNameUrl(String old) {
+        Stapler.getCurrentRequest().setAttribute("currentDescriptorByNameUrl", old);
+    }
 }

core/src/main/resources/lib/form/withCustomDescriptorByName.jelly

+<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:i="jelly:fmt">
+  <st:documentation>
+    Execute the body with a temporary currentDescriptorByNameUrl value
+
+    <st:attribute name="value" use="required">
+    </st:attribute>
+  </st:documentation>
+
+  <j:set var="old" value="${h.setCurrentDescriptorByNameUrl(attrs.value)}"/>
+  <d:invokeBody/>
+  <j:set var="_" value="${h.restoreCurrentDescriptorByNameUrl(old)}"/>
+</j:jelly>
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