listen to touch hook to update the mtime after sync

lib/files/cache/updater.php

@@ -128,6 +128,13 @@ class Updater {
 		self::writeUpdate($params['path']);
 	}
 
+	/**
+	 * @param array $params
+	 */
+	static public function touchHook($params) {
+		self::writeUpdate($params['path']);
+	}
+
 	/**
 	 * @param array $params
 	 */

lib/files/filesystem.php

@@ -661,6 +661,7 @@ class Filesystem {
 }
 
 \OC_Hook::connect('OC_Filesystem', 'post_write', '\OC\Files\Cache\Updater', 'writeHook');
+\OC_Hook::connect('OC_Filesystem', 'post_touch', '\OC\Files\Cache\Updater', 'touchHook');
 \OC_Hook::connect('OC_Filesystem', 'post_delete', '\OC\Files\Cache\Updater', 'deleteHook');
 \OC_Hook::connect('OC_Filesystem', 'post_rename', '\OC\Files\Cache\Updater', 'renameHook');