Index: modules/block/block.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/block/block.module,v
retrieving revision 1.429
diff -u -p -r1.429 block.module
--- modules/block/block.module	18 Sep 2010 02:18:35 -0000	1.429
+++ modules/block/block.module	21 Sep 2010 22:31:02 -0000
@@ -804,17 +804,25 @@ function block_block_list_alter(&$blocks
  *   An array of visible blocks as expected by drupal_render().
  */
 function _block_render_blocks($region_blocks) {
+  // Keep cache enabled as a static variable because this method will be called
+  // for each region.
+  static $cache_enabled;
+
+  // Block caching is not compatible with node_access modules.
+  if (!isset($cache_enabled)) {
+    $cache_enabled = &drupal_static(__FUNCTION__, !count(module_implements('node_grants')));
+  }
+
   foreach ($region_blocks as $key => $block) {
     // Render the block content if it has not been created already.
     if (!isset($block->content)) {
       // Erase the block from the static array - we'll put it back if it has
       // content.
       unset($region_blocks[$key]);
-      // Try fetching the block from cache. Block caching is not compatible
-      // with node_access modules. We also preserve the submission of forms in
-      // blocks, by fetching from cache only if the request method is 'GET'
-      // (or 'HEAD').
-      if (!count(module_implements('node_grants')) && ($_SERVER['REQUEST_METHOD'] == 'GET' || $_SERVER['REQUEST_METHOD'] == 'HEAD') && ($cid = _block_get_cache_id($block)) && ($cache = cache_get($cid, 'cache_block'))) {
+      // Try fetching the block from cache. We also preserve the submission of
+      // forms in blocks, by fetching from cache only if the request method is
+      // 'GET' (or 'HEAD').
+      if ($cache_enabled && ($_SERVER['REQUEST_METHOD'] == 'GET' || $_SERVER['REQUEST_METHOD'] == 'HEAD') && ($cid = _block_get_cache_id($block)) && ($cache = cache_get($cid, 'cache_block'))) {
         $array = $cache->data;
       }
       else {