cache list parameter to avoid unnecessary rpc transmissions

vispa/remote/filesystem.py

@@ -103,7 +103,7 @@ class FileSystem(object):
     def get_file_list(self, path, deep=False,
                       filter=None, reverse=False,
                       hide_hidden=True, encode_json=True):
-        filter = filter or []
+        filter = filter[:] or []
         filelist = []
         path_expand = self.expand(path)
         try: