Make `$blog_id` explicitly global.

`$blog_id` is used in both single and multisite configurations as a global variable, though has never been explicitly marked as such in the global scope. This can cause confusion depending on how core is loaded.

Fixes #34217.

Built from https://develop.svn.wordpress.org/trunk@34961


git-svn-id: http://core.svn.wordpress.org/trunk@34926 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/default-constants.php

@@ -11,6 +11,8 @@
  * @see wp_debug_mode()
  *
  * @since 3.0.0
+ *
+ * @global int $blog_id
  */
 function wp_initial_constants() {
 	global $blog_id;
@@ -28,13 +30,6 @@ function wp_initial_constants() {
 		define( 'WP_MAX_MEMORY_LIMIT', '256M' );
 	}
 
-	/**
-	 * The $blog_id global, which you can change in the config allows you to create a simple
-	 * multiple blog installation using just one WordPress and changing $blog_id around.
-	 *
-	 * @global int $blog_id
-	 * @since 2.0.0
-	 */
 	if ( ! isset($blog_id) )
 		$blog_id = 1;
 

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-34960';
+$wp_version = '4.4-alpha-34961';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.

wp-settings.php

@@ -29,6 +29,15 @@ require( ABSPATH . WPINC . '/default-constants.php' );
 global $wp_version, $wp_db_version, $tinymce_version, $required_php_version, $required_mysql_version;
 require( ABSPATH . WPINC . '/version.php' );
 
+/**
+ * If not already configured, `$blog_id` will default to 1 in a single site
+ * configuration. In multisite, it will be overridden by default in ms-settings.php.
+ *
+ * @global int $blog_id
+ * @since 2.0.0
+ */
+global $blog_id;
+
 // Set initial default constants including WP_MEMORY_LIMIT, WP_MAX_MEMORY_LIMIT, WP_DEBUG, SCRIPT_DEBUG, WP_CONTENT_DIR and WP_CACHE.
 wp_initial_constants();