Multisite: Support the $network_id parameter of get_blog_count().

The `get_blog_count()` function used to support an `$id` parameter for the network ID prior to WordPress 3.1. This parameter has not been used since the introduction of `get_site_option()` and was later deprecated in [25113]. With `get_network_option()` however it is possible to support the parameter again, now properly renamed as `$network_id`.

A unit test has for the parameter has been added as well. Another unit test in the same class was adjusted to work properly with multiple networks existing.

Fixes #37865.

Built from https://develop.svn.wordpress.org/trunk@40370


git-svn-id: http://core.svn.wordpress.org/trunk@40277 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/ms-functions.php

@@ -109,15 +109,14 @@ function get_user_count() {
  * The count is cached and updated twice daily. This is not a live count.
  *
  * @since MU 1.0
+ * @since 3.7.0 The $network_id parameter has been deprecated.
+ * @since 4.8.0 The $network_id parameter is now being used.
  *
- * @param int $network_id Deprecated, not supported.
- * @return int
+ * @param int|null $network_id ID of the network. Default is the current network.
+ * @return int Number of active sites on the network.
  */
-function get_blog_count( $network_id = 0 ) {
-	if ( func_num_args() )
-		_deprecated_argument( __FUNCTION__, '3.1.0' );
-
-	return get_site_option( 'blog_count' );
+function get_blog_count( $network_id = null ) {
+	return get_network_option( $network_id, 'blog_count' );
 }
 
 /**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-40368';
+$wp_version = '4.8-alpha-40370';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.