[gegl] brightness-contrast: propagate BablSpace

[Øyvind "pippin" Kolås <ok src gnome org>]

commit dcd7ef04e3ea7854f8689b649164e0783f2f5956
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Jul 5 13:51:14 2018 +0200

    brightness-contrast: propagate BablSpace

 operations/common/brightness-contrast.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/operations/common/brightness-contrast.c b/operations/common/brightness-contrast.c
index e81773162..4a22541b6 100644
--- a/operations/common/brightness-contrast.c
+++ b/operations/common/brightness-contrast.c
@@ -75,8 +75,9 @@ property_double (brightness, _("Brightness"), 0.0)
  */
 static void prepare (GeglOperation *operation)
 {
-  gegl_operation_set_format (operation, "input", babl_format ("RGBA float"));
-  gegl_operation_set_format (operation, "output", babl_format ("RGBA float"));
+  const Babl *space = gegl_operation_get_source_space (operation, "input");
+  gegl_operation_set_format (operation, "input", babl_format_with_space ("RGBA float", space));
+  gegl_operation_set_format (operation, "output", babl_format_with_space ("RGBA float", space));
 }
 
 /* For GeglOperationPointFilter subclasses, we operate on linear