Issue #1297370 by moshe weitzman, webchick: Fixed Default installation of D8 shows help region.

modules/block/block.module

@@ -850,7 +850,7 @@ function _block_get_renderable_block($element) {
     // hook_block_view_alter() or hook_block_view_MODULE_DELTA_alter().
     drupal_alter(array('block_view', "block_view_{$block->module}_{$block->delta}"), $array, $block);
 
-    if (empty($array)) {
+    if (empty($array['content'])) {
       // Blocks without content should emit no markup at all.
       $element += array(
         '#access' => FALSE,

modules/block/block.test

@@ -190,6 +190,9 @@ class BlockTestCase extends DrupalWebTestCase {
     $this->drupalLogout();
     $this->drupalGet('');
     $this->assertNoText($title, t('Block was not displayed to anonymous users.'));
+
+    // Confirm that an empty block is not displayed.
+    $this->assertNoRaw('block-system-help', t('Empty block not displayed.'));
   }
 
   /**

modules/book/book.module

@@ -274,8 +274,9 @@ function book_block_view($delta = '') {
         $book_menus[$book_id] = menu_tree_output($pseudo_tree);
       }
     }
-    $book_menus['#theme'] = 'book_all_books_block';
-    $block['content'] = $book_menus;
+    if ($block['content'] = $book_menus) {
+      $book_menus['#theme'] = 'book_all_books_block';
+    }
   }
   elseif ($current_bid) {
     // Only display this block when the user is browsing a book.