[HUDSON-4822] patch from lkishalmi to return after sending redirect in doLoginEntry

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@23678 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/Hudson.java

@@ -2641,8 +2641,10 @@ public final class Hudson extends Node implements ItemGroup<TopLevelItem>, Stapl
      * Called once the user logs in. Just forward to the top page.
      */
     public void doLoginEntry( StaplerRequest req, StaplerResponse rsp ) throws IOException {
-        if(req.getUserPrincipal()==null)
+        if(req.getUserPrincipal()==null) {
             rsp.sendRedirect2("noPrincipal");
+            return;
+        }
 
         String from = req.getParameter("from");
         if(from!=null && from.startsWith("/") && !from.equals("/loginError")) {