[gnome-session] check-accelerated: only cache result if successful

[Ray Strode <halfline src gnome org>]

commit 8a253eb715a3fe496bc8b51041dfa4b0fecbf2bd
Author: Ray Strode <rstrode redhat com>
Date:   Tue Mar 5 22:38:24 2013 -0500

    check-accelerated: only cache result if successful
    
    If it's unsuccessful it may be successful in a subsequent run,
    so caching it can cause problems.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=672943

 tools/gnome-session-check-accelerated.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/tools/gnome-session-check-accelerated.c b/tools/gnome-session-check-accelerated.c
index 2bd7993..3f10778 100644
--- a/tools/gnome-session-check-accelerated.c
+++ b/tools/gnome-session-check-accelerated.c
@@ -168,10 +168,12 @@ main (int argc, char **argv)
                         g_printerr ("gnome-session-check-accelerated: Helper exited with code %d\n", 
estatus);
         }
 
-        XChangeProperty (GDK_DISPLAY_XDISPLAY (display),
-                         rootwin,
-                         is_accelerated_atom,
-                         XA_CARDINAL, 32, PropModeReplace, (guchar *) &is_accelerated, 1);
+        if (is_accelerated) {
+            XChangeProperty (GDK_DISPLAY_XDISPLAY (display),
+                             rootwin,
+                             is_accelerated_atom,
+                             XA_CARDINAL, 32, PropModeReplace, (guchar *) &is_accelerated, 1);
+        }
 
         gdk_display_sync (display);