[gegl] gegl: check if babl format exists when parsing format props

[Øyvind Kolås <ok src gnome org>]

commit 36b478a89ff21f13ac7c53a2902b7b4b9754d4bb
Author: Øyvind Kolås <pippin gimp org>
Date:   Mon Nov 27 15:15:11 2017 +0100

    gegl: check if babl format exists when parsing format props
    
    As suggested by massimo in bug #790885

 gegl/gegl-serialize.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gegl/gegl-serialize.c b/gegl/gegl-serialize.c
index 9a5b7da..ee56f67 100644
--- a/gegl/gegl-serialize.c
+++ b/gegl/gegl-serialize.c
@@ -490,7 +490,7 @@ gegl_create_chain_argv (char      **ops,
                       {
                         const Babl *format = NULL;
 
-                        if (value[0])
+                        if (value[0] && babl_format_exists (value))
                           format = babl_format (value);
 
                         gegl_node_set (iter[level], key, format, NULL);