Move database class loading to a shared function to ensure all of WordPress is wp-content/wp-db.php aware. Fixes #5128 props ComputerGuru.

git-svn-id: http://svn.automattic.com/wordpress/trunk@6198 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -1415,4 +1415,21 @@ function wp_ob_end_flush_all()
 	while ( @ob_end_flush() );
 }
 
+/*
+ * require_wp_db() - require_once the correct database class file.
+ *
+ * This function is used to load the database class file either at runtime or by wp-admin/setup-config.php
+ * We must globalise $wpdb to ensure that it is defined globally by the inline code in wp-db.php
+ *
+ * @global $wpdb
+ */
+function require_wp_db()
+{
+	global $wpdb;
+	if ( file_exists(ABSPATH . 'wp-content/db.php') )
+		require_once (ABSPATH . 'wp-content/db.php');
+	else
+		require_once (ABSPATH . WPINC . '/wp-db.php');
+}
+
 ?>