Index: modules/comment/comment.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/comment/comment.install,v
retrieving revision 1.73
diff -u -p -r1.73 comment.install
--- modules/comment/comment.install	28 Sep 2010 03:30:37 -0000	1.73
+++ modules/comment/comment.install	9 Dec 2010 21:58:33 -0000
@@ -8,6 +8,8 @@
 
 /**
  * Implements hook_install().
+ *
+ * @see comment_flush_caches()
  */
 function comment_install() {
   // Create comment body field.
@@ -19,20 +21,6 @@ function comment_install() {
     );
     field_create_field($field);
   }
-
-  // There is a separate comment bundle for each node type to allow for
-  // per-node-type customization of comment fields. Each one of these bundles
-  // needs a comment body field instance. A comment bundle is needed even for
-  // node types whose comments are disabled by default, because individual nodes
-  // may override that default.
-  // @todo This should be changed to call field_attach_create_bundle() instead,
-  //   and a comment_field_attach_create_bundle() function should be added to
-  //   handle the creation of the comment body field instance.
-  foreach (node_type_get_types() as $type => $info) {
-    if (!isset($info->is_new) && !isset($info->disabled) && !field_info_instance('comment', 'comment_body', 'comment_node_' . $info->type)) {
-      _comment_body_field_instance_create($info);
-    }
-  }
 }
 
 /**
Index: modules/comment/comment.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/comment/comment.module,v
retrieving revision 1.927
diff -u -p -r1.927 comment.module
--- modules/comment/comment.module	9 Dec 2010 01:57:56 -0000	1.927
+++ modules/comment/comment.module	9 Dec 2010 21:58:34 -0000
@@ -2689,3 +2689,28 @@ function comment_file_download_access($f
     return user_access('access comments') && $entity->status == COMMENT_PUBLISHED || user_access('administer comments');
   }
 }
+
+/**
+ * Implements hook_flush_caches().
+ *
+ * This hook is invoked after groups of modules are installed or enabled. This
+ * is the first time we have access to a rebuilt node type list. Create comment
+ * body field and/or field instances for each node type in the rebuilt list.
+ *
+ * @see comment_install()
+ */
+function comment_flush_caches() {
+  // There is a separate comment bundle for each node type to allow for
+  // per-node-type customization of comment fields. Each one of these bundles
+  // needs a comment body field instance. A comment bundle is needed even for
+  // node types whose comments are disabled by default, because individual nodes
+  // may override that default.
+  // @todo This should be changed to call field_attach_create_bundle() instead,
+  //   and a comment_field_attach_create_bundle() function should be added to
+  //   handle the creation of the comment body field instance.
+  foreach (node_type_get_types() as $type => $info) {
+    if (empty($info->is_new) && empty($info->disabled) && !field_info_instance('comment', 'comment_body', 'comment_node_' . $info->type)) {
+      _comment_body_field_instance_create($info);
+    }
+  }
+}
Index: modules/comment/comment.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/comment/comment.test,v
retrieving revision 1.95
diff -u -p -r1.95 comment.test
--- modules/comment/comment.test	9 Dec 2010 02:16:21 -0000	1.95
+++ modules/comment/comment.test	9 Dec 2010 21:58:34 -0000
@@ -1478,3 +1478,34 @@ class CommentActionsTestCase extends Com
     db_truncate('watchdog')->execute();
   }
 }
+
+/**
+ * Test that comment module works after being enabled after a content module.
+ */
+class CommentEnableTest extends CommentHelperCase {
+  protected $profile = 'testing';
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Comment enable test',
+      'description' => 'Test that comment module works after being enabled after a content module.',
+      'group' => 'Comment',
+    );
+  }
+
+  function setUp() {
+    // Do not call parent::setUp() because we selectively enable modules.
+    DrupalWebTestCase::setUp(array('blog', 'comment'));
+    // Create a user and test node.
+    $this->web_user = $this->drupalCreateUser(array('access comments', 'post comments', 'skip comment approval'));
+    $this->node = $this->drupalCreateNode(array('type' => 'blog'));
+  }
+
+  /**
+   * Test that comment module works after being enabled after a content module.
+   */
+  function testCommentEnable() {
+    $this->drupalLogin($this->web_user);
+    $comment = $this->postComment($this->node, $this->randomName(), $this->randomName());
+  }
+}
Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.1330
diff -u -p -r1.1330 node.module
--- modules/node/node.module	2 Dec 2010 23:58:21 -0000	1.1330
+++ modules/node/node.module	9 Dec 2010 21:58:34 -0000
@@ -672,10 +672,14 @@ function node_type_update_nodes($old_typ
  */
 function _node_types_build($rebuild = FALSE) {
   $cid = 'node_types:' . $GLOBALS['language']->language;
+  $_node_types = &drupal_static(__FUNCTION__, (object) array('init' => TRUE, 'types' => array(), 'names' => array()));
 
-  if (!$rebuild) {
-    $_node_types = &drupal_static(__FUNCTION__);
-    if (isset($_node_types)) {
+  if ($rebuild) {
+    // Reset the static cache.
+    $_node_types->types = $_node_types->names = array();
+  }
+  else {
+    if (!isset($_node_types->init)) {
       return $_node_types;
     }
     if ($cache = cache_get($cid)) {
@@ -683,8 +687,8 @@ function _node_types_build($rebuild = FA
       return $_node_types;
     }
   }
-
-  $_node_types = (object) array('types' => array(), 'names' => array());
+  // Unset internal initialization flag.
+  unset($_node_types->init);
 
   foreach (module_implements('node_info') as $module) {
     $info_array = module_invoke($module, 'node_info');
@@ -734,6 +738,8 @@ function _node_types_build($rebuild = FA
     foreach ($_node_types->types as $type => $type_object) {
       if (!empty($type_object->is_new) || !empty($type_object->disabled_changed)) {
         node_type_save($type_object);
+        // Since the type has been saved, the is_new flag is no longer needed.
+        unset($_node_types->types[$type]->is_new);
       }
     }
   }
Index: modules/node/node.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.test,v
retrieving revision 1.104
diff -u -p -r1.104 node.test
--- modules/node/node.test	9 Dec 2010 08:01:56 -0000	1.104
+++ modules/node/node.test	9 Dec 2010 21:58:35 -0000
@@ -1220,6 +1220,21 @@ class NodeTypeTestCase extends DrupalWeb
     $this->drupalGet('node/add/bar');
     $this->assertNoRaw('Body', t('Body field was not found.'));
   }
+
+  /**
+   * Test that fresh node types are returned by node_type_get_types().
+   */
+  function testNodeTypeCaching() {
+    // Prime the node type cache.
+    node_types_rebuild();
+    // Enable the blog module, which provides a content type.
+    module_enable(array('blog'), FALSE);
+    $this->resetAll();
+    // node_type_get_types() should include the new type.
+    $new_types = node_type_get_types();
+    $this->assertTrue(isset($new_types['blog']), t('Retrieved node types include new type.'));
+    $this->assertTrue(empty($new_types['blog']->is_new), t('The is_new flag was unset after the type was saved.'));
+  }
 }
 
 /**