[gegl] gegl: gegl_node_blit only compute auto-rowstride if we also got passed format

[Øyvind Kolås <ok src gnome org>]

commit bab70d17fbe91befc12ebc911b7f83b3d90d76e8
Author: Øyvind Kolås <pippin gimp org>
Date:   Sun Jul 6 02:03:28 2014 +0200

    gegl: gegl_node_blit only compute auto-rowstride if we also got passed format

 gegl/graph/gegl-node.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gegl/graph/gegl-node.c b/gegl/graph/gegl-node.c
index c6b38e2..05381d7 100644
--- a/gegl/graph/gegl-node.c
+++ b/gegl/graph/gegl-node.c
@@ -1003,7 +1003,7 @@ gegl_node_blit (GeglNode            *self,
   g_return_if_fail (GEGL_IS_NODE (self));
   g_return_if_fail (roi != NULL);
 
-  if (rowstride == GEGL_AUTO_ROWSTRIDE)
+  if (rowstride == GEGL_AUTO_ROWSTRIDE && format)
     rowstride = babl_format_get_bytes_per_pixel (format) * roi->width;
 
   if (!flags)