[gegl] processor: Fix construction with a non-NULL rectangle

[Debarshi Ray <debarshir src gnome org>]

commit 91b217d4e8f57a1204e5793e3aa66be6fac18299
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon Dec 7 20:29:46 2015 +0100

    processor: Fix construction with a non-NULL rectangle
    
    Ensure that the graph is prepared whenever a new GeglNode is set.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=759137

 gegl/process/gegl-processor.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gegl/process/gegl-processor.c b/gegl/process/gegl-processor.c
index 0f23bd9..08854a2 100644
--- a/gegl/process/gegl-processor.c
+++ b/gegl/process/gegl-processor.c
@@ -288,6 +288,9 @@ gegl_processor_set_node (GeglProcessor *processor,
 
   g_return_if_fail (processor->input != NULL);
 
+  /* Prepare the graph */
+  gegl_node_get_bounding_box (processor->input);
+
   g_object_ref (processor->input);
 
   g_object_notify (G_OBJECT (processor), "node");