[meld/ui-next] tree: Fix sensitivity setting for rows without a path

[Kai Willadsen <kaiw src gnome org>]

commit a556565f656fa4c88c4f0b74b32ad3914e3e48b7
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Fri Feb 22 11:29:41 2019 +1000

    tree: Fix sensitivity setting for rows without a path

 meld/tree.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meld/tree.py b/meld/tree.py
index 8bca4fd8..f4d853fe 100644
--- a/meld/tree.py
+++ b/meld/tree.py
@@ -121,7 +121,7 @@ class DiffTreeStore(SearchableTreeStore):
         # A folder may no longer exist, and is only tracked by VC.
         # Therefore, check the icon instead, as the pane already knows.
         icon = self.get_value(it, self.column_index(COL_ICON, pane))
-        return icon == "folder" or os.path.isdir(path)
+        return icon == "folder" or (bool(path) and os.path.isdir(path))
 
     def column_index(self, col, pane):
         return self.ntree * col + pane