provide some helpful description instead of empty page, if the polling hasn't run yet.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@1151 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/resources/hudson/triggers/SCMTrigger/SCMAction/index.jelly

@@ -3,7 +3,15 @@
     <st:include it="${it.owner}" page="sidepanel.jelly" />
     <l:main-panel>
       <h1>Last ${it.displayName}</h1>
-      <pre>${it.log}</pre>
+      <j:set var="log" value="${it.log}" />
+      <j:choose>
+        <j:when test="${empty(log)}">
+          Polling has not run yet.
+        </j:when>
+        <j:otherwise>
+          <pre>${it.log}</pre>
+        </j:otherwise>
+      </j:choose>
     </l:main-panel>
   </l:layout>
 </j:jelly>