[gnome-desktop] don't try to scale null images

[William Jon McCann <mccann src gnome org>]

commit c68c8122a761fe22f09d56dbf863eeaaabd4a3ee
Author: William Jon McCann <jmccann redhat com>
Date:   Thu Dec 10 17:32:58 2009 -0500

    don't try to scale null images

 libgnome-desktop/gnome-bg.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/libgnome-desktop/gnome-bg.c b/libgnome-desktop/gnome-bg.c
index c584147..f050e70 100644
--- a/libgnome-desktop/gnome-bg.c
+++ b/libgnome-desktop/gnome-bg.c
@@ -1843,10 +1843,10 @@ create_img_thumbnail (GnomeBG                      *bg,
 					FileSize *fs;
 					fs = find_best_size (slide->file1, dest_width, dest_height);
 					tmp = get_as_thumbnail (bg, factory, fs->file);
-
-					thumb = scale_thumbnail (
-						bg->placement, fs->file,
-						tmp, screen, dest_width, dest_height);
+					if (tmp)
+						thumb = scale_thumbnail (
+									 bg->placement, fs->file,
+									 tmp, screen, dest_width, dest_height);
 				}
 				else {
 					FileSize *fs1, *fs2;