[gegl] copy-buffer: add expected passthrough ref hash

[Øyvind Kolås <ok src gnome org>]

commit 008a80b98df9a5395ce589fd0e40f081173b7581
Author: Øyvind Kolås <pippin gimp org>
Date:   Sun Apr 30 23:11:03 2017 +0200

    copy-buffer: add expected passthrough ref hash

 operations/common/copy-buffer.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/operations/common/copy-buffer.c b/operations/common/copy-buffer.c
index b7c1707..c10c6b0 100644
--- a/operations/common/copy-buffer.c
+++ b/operations/common/copy-buffer.c
@@ -148,10 +148,11 @@ gegl_op_class_init (GeglOpClass *klass)
   filter_class->process     = process;
 
   gegl_operation_class_set_keys (operation_class,
-    "name",        "gegl:copy-buffer",
-    "title",       _("Copy Buffer"),
-    "categories" , "programming",
-    "description", _("Writes image data to an already existing buffer"),
+    "name",           "gegl:copy-buffer",
+    "title",          _("Copy Buffer"),
+    "categories" ,    "programming",
+    "reference-hash", "9bbe341d798da4f7b181c903e6f442fd",
+    "description",    _("Writes image data to an already existing buffer"),
     NULL);
 }