MS: Handle the possibility of 0 when checking a user's upload quota.

Upload space of 0 is now more possible via r35016 and should be respected rather than modified to a default of 10MB.

Fixes #34037.

Built from https://develop.svn.wordpress.org/trunk@35017


git-svn-id: http://core.svn.wordpress.org/trunk@34982 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/ms.php

@@ -417,9 +417,9 @@ function upload_is_user_over_quota( $echo = true ) {
 		return false;
 
 	$space_allowed = get_space_allowed();
-	if ( empty( $space_allowed ) || !is_numeric( $space_allowed ) )
+	if ( ! is_numeric( $space_allowed ) ) {
 		$space_allowed = 10; // Default space allowed is 10 MB
-
+	}
 	$space_used = get_space_used();
 
 	if ( ( $space_allowed - $space_used ) < 0 ) {