[meld] iohelpers: Some minor mypy pacification

[Kai Willadsen <kaiw src gnome org>]

commit d0370bf2f8dc56a5f775abcfef13b7c79351e45e
Author: Me <me example com>
Date:   Sat Jul 27 07:59:37 2019 +1000

    iohelpers: Some minor mypy pacification

 meld/iohelpers.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/meld/iohelpers.py b/meld/iohelpers.py
index 53006475..28c13155 100644
--- a/meld/iohelpers.py
+++ b/meld/iohelpers.py
@@ -92,14 +92,18 @@ def prompt_save_filename(
 
     try:
         file_info = gfile.query_info(
-            'standard::name,standard::display-name', 0, None)
+            'standard::name,standard::display-name',
+            Gio.FileQueryInfoFlags.NONE,
+            None,
+        )
     except GLib.Error as err:
         if err.code == Gio.IOErrorEnum.NOT_FOUND:
             return gfile
         raise
 
     # The selected file exists, so we need to prompt for overwrite.
-    parent_name = gfile.get_parent().get_parse_name()
+    parent_folder = gfile.get_parent()
+    parent_name = parent_folder.get_parse_name() if parent_folder else ''
     file_name = file_info.get_display_name()
 
     replace = modal_dialog(