#678536 by jhodgdon: Improve error message when adding forum topic directly to container.

modules/forum/forum.module

@@ -286,7 +286,7 @@ function forum_node_validate($node, $form) {
           ':vid' => $term->vid,
         ))->fetchField();
         if ($used && in_array($term->tid, $containers)) {
-          form_set_error('taxonomy_forums', t('The item %forum is only a forum container. Select one of the forums below it.', array('%forum' => $term->name)));
+          form_set_error('taxonomy_forums', t('The item %forum is a forum container, not a forum. Select one of the forums below instead.', array('%forum' => $term->name)));
         }
       }
     }

modules/forum/forum.test

@@ -281,12 +281,12 @@ class ForumTestCase extends DrupalWebTestCase {
     $type = t('Forum topic');
     if ($container) {
       $this->assertNoRaw(t('@type %title has been created.', array('@type' => $type, '%title' => $title)), t('Forum topic was not created'));
-      $this->assertRaw(t('The item %title is only a forum container.', array('%title' => $forum['name'])), t('Error message was shown'));
+      $this->assertRaw(t('The item %title is a forum container, not a forum.', array('%title' => $forum['name'])), t('Error message was shown'));
       return;
     }
     else {
       $this->assertRaw(t('@type %title has been created.', array('%title' => $title, '@type' => $type)), t('Forum topic was created'));
-      $this->assertNoRaw(t('The item %title is only a forum container.', array('%title' => $forum['name'])), t('No error message was shown'));
+      $this->assertNoRaw(t('The item %title is a forum container, not a forum.', array('%title' => $forum['name'])), t('No error message was shown'));
     }
 
     // Retrieve node object.