Use pane_current_path instead of pane_start_path

tmux 1.9 removed the latter

Author: ThiefMaster

tmuxp/testsuite/workspacebuilder.py

@@ -429,7 +429,7 @@ def test_start_directory(self):
         dirs = ['/usr/bin', '/dev', '/tmp/foo bar', '/usr', os.getcwd()]
         for path, window in zip(dirs, self.session.windows):
             for p in window.panes:
-                self.assertEqual(p.get('pane_start_path'), path)
+                self.assertEqual(p.get('pane_current_path'), path)
 
 
 class PaneOrderingTest(TmuxTestCase):