[gdk-pixbuf] Avoid a compiler warning

[Matthias Clasen <matthiasc src gnome org>]

commit 8c2699bf8bbd189b7869c2498f1bcbba6057ed7e
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Dec 18 23:21:55 2013 -0500

    Avoid a compiler warning
    
    Harmless NULL / FALSE confusion.

 gdk-pixbuf/gdk-pixbuf-io.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gdk-pixbuf/gdk-pixbuf-io.c b/gdk-pixbuf/gdk-pixbuf-io.c
index 3d9739d..0ef83b4 100644
--- a/gdk-pixbuf/gdk-pixbuf-io.c
+++ b/gdk-pixbuf/gdk-pixbuf-io.c
@@ -2927,7 +2927,7 @@ gdk_pixbuf_save_to_stream_finish (GAsyncResult  *async_result,
        /* Can not use g_task_is_valid because our GTask has a
         * source_object which is not available to us anymore.
         */
-       g_return_val_if_fail (G_IS_TASK (async_result), NULL);
+       g_return_val_if_fail (G_IS_TASK (async_result), FALSE);
 
        task = G_TASK (async_result);