Index: src/wp-admin/includes/plugin.php
===================================================================
--- src/wp-admin/includes/plugin.php	(revision 52691)
+++ src/wp-admin/includes/plugin.php	(working copy)
@@ -369,6 +369,9 @@
 	$plugins_dir = @opendir( WPMU_PLUGIN_DIR );
 	if ( $plugins_dir ) {
 		while ( ( $file = readdir( $plugins_dir ) ) !== false ) {
+			if ( '.' === substr( $file, 0, 1 ) ) {
+				continue;
+			}
 			if ( '.php' === substr( $file, -4 ) ) {
 				$plugin_files[] = $file;
 			}