[meld: 4/8] fix code to pass the lint check

[Kai Willadsen <kaiw src gnome org>]

commit 8292e53d883e35128d4949fff9f77a23e9d71f90
Author: Helly Guo <buffoonguo gmail com>
Date:   Wed Feb 16 09:20:51 2022 +0800

    fix code to pass the lint check

 meld/dirdiff.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/meld/dirdiff.py b/meld/dirdiff.py
index 767d9e1f..2e894088 100644
--- a/meld/dirdiff.py
+++ b/meld/dirdiff.py
@@ -1277,8 +1277,9 @@ class DirDiff(Gtk.VBox, tree.TreeviewCommon, MeldDoc):
             self.set_action_enabled('folder-expand', is_single_foldable_row)
             self.set_action_enabled('folder-compare', True)
             self.set_action_enabled('folder-mark', True)
-            self.set_action_enabled('folder-unmark', self.marked != None)
-            self.set_action_enabled('folder-compare-marked', self.marked != None)
+            self.set_action_enabled('folder-unmark', self.marked is not None)
+            self.set_action_enabled(
+                'folder-compare-marked', self.marked is not None)
             self.set_action_enabled('folder-delete', is_valid)
             self.set_action_enabled('folder-copy-left', is_valid and pane > 0)
             self.set_action_enabled(