[meld] filediff: Prevent AttributeError when pane has no file

[Kai Willadsen <kaiw src gnome org>]

commit 59c947c8f43d2a65800ecade8b4a922aa8e7bc8f
Author: Claude Paroz <claude 2xlibre net>
Date:   Mon Oct 24 16:33:53 2016 +0200

    filediff: Prevent AttributeError when pane has no file

 meld/filediff.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/meld/filediff.py b/meld/filediff.py
index c21653e..ff0ab46 100644
--- a/meld/filediff.py
+++ b/meld/filediff.py
@@ -1579,7 +1579,7 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
         entries = self.fileentry[:self.num_panes]
         if self.check_save_modified() != Gtk.ResponseType.CANCEL:
             files = [e.get_file() for e in entries]
-            paths = [f.get_path() for f in files]
+            paths = [f.get_path() if f is not None else f for f in files]
             self.set_files(paths)
         else:
             idx = entries.index(entry)