Add stage base class, refactor discovery, etc
diff --git a/wally/suits/io/fio.py b/wally/suits/io/fio.py
index 0f4ebde..1b5f38e 100644
--- a/wally/suits/io/fio.py
+++ b/wally/suits/io/fio.py
@@ -83,7 +83,7 @@
             node.conn.rmdir(self.config.remote_dir, recursive=True, ignore_missing=True)
             node.conn.mkdir(self.config.remote_dir)
         except Exception as exc:
-            msg = "Failed to create folder {} on remote {}.".format(self.config.remote_dir, node, exc)
+            msg = "Failed to create folder {} on remote {}.".format(self.config.remote_dir, node)
             logger.exception(msg)
             raise StopTestError(msg) from exc