Index: wp-includes/class-wp-editor.php
===================================================================
--- wp-includes/class-wp-editor.php	(revision 19628)
+++ wp-includes/class-wp-editor.php	(working copy)
@@ -208,10 +208,13 @@
 							}
 						}
 
+						self::$ext_plugins .= $ext_plugins;
+
 						foreach ( $mce_external_plugins as $name => $url ) {
 
 							if ( is_ssl() ) $url = str_replace('http://', 'https://', $url);
 
+							$ext_plugins = '';
 							$plugins[] = '-' . $name;
 
 							$plugurl = dirname($url);