[pygobject] tests: Fix crash with empty drag source icon names

[Simon Feltman <sfeltman src gnome org>]

commit 8145fa69c8ace9772687f26f782acb5e461776be
Author: Simon Feltman <sfeltman src gnome org>
Date:   Sat Feb 20 17:32:01 2016 -0800

    tests: Fix crash with empty drag source icon names
    
    Add "_About" argument when testing call to drag_source_set_icon_name().
    Add Gtk.STOCK_ABOUT argument when testing call to drag_source_set_icon_stock().
    This avoids crashes due to GTK+ drag source attempting to unref a NULL pointer.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=762392

 tests/test_overrides_gtk.py |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/tests/test_overrides_gtk.py b/tests/test_overrides_gtk.py
index 9aa592c..f184152 100644
--- a/tests/test_overrides_gtk.py
+++ b/tests/test_overrides_gtk.py
@@ -516,9 +516,9 @@ class TestGtk(unittest.TestCase):
         widget.drag_source_add_image_targets()
         widget.drag_source_add_text_targets()
         widget.drag_source_add_uri_targets()
-        widget.drag_source_set_icon_name("")
+        widget.drag_source_set_icon_name("_About")
         widget.drag_source_set_icon_pixbuf(GdkPixbuf.Pixbuf())
-        widget.drag_source_set_icon_stock("")
+        widget.drag_source_set_icon_stock(Gtk.STOCK_ABOUT)
         widget.drag_source_get_target_list()
         widget.drag_source_set_target_list(None)
         widget.drag_source_set_target_list(Gtk.TargetList.new([Gtk.TargetEntry.new('test', 0, 0)]))