fixed NPE

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@6993 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/security/HudsonPrivateSecurityRealm.java

@@ -200,7 +200,7 @@ public class HudsonPrivateSecurityRealm extends SecurityRealm {
                 if(data.startsWith(prefix))
                     return new Details(data.substring(prefix.length()));
             }
-            return new Details(pwd);
+            return new Details(Util.fixNull(pwd));
         }
 
         public boolean isEnabled() {