[meld/pathlabel] ui.pathlabel: Use the plain descendent file as label when missing parent

[Kai Willadsen <kaiw src gnome org>]

commit 9e18903b4381fc17a27b40f5fbac5e30e0179aab
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Jan 17 07:41:26 2021 +1000

    ui.pathlabel: Use the plain descendent file as label when missing parent

 meld/ui/pathlabel.py | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/meld/ui/pathlabel.py b/meld/ui/pathlabel.py
index e04f8768..ff9a532f 100644
--- a/meld/ui/pathlabel.py
+++ b/meld/ui/pathlabel.py
@@ -158,6 +158,12 @@ class PathLabel(Gtk.MenuButton):
         if not parent or not descendant:
             self._parent_gfile = parent
             self._gfile = descendant
+
+            # If we have no parent yet but have a descendant, we'll use
+            # the descendant name as the better-than-nothing label.
+            if descendant:
+                self._path_label = descendant.get_parse_name()
+                self.notify('path_label')
             return
 
         descendant_parent = descendant.get_parent()