[gegl] gegl:gegl fix broken refactoring in previous commit

[Øyvind Kolås <ok src gnome org>]

commit 314844eca03320b19a1e0a0a43561609235dfa94
Author: Øyvind Kolås <pippin gimp org>
Date:   Sat Apr 16 02:35:52 2016 +0100

    gegl:gegl fix broken refactoring in previous commit

 operations/common/gegl.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
---
diff --git a/operations/common/gegl.c b/operations/common/gegl.c
index 0a5a4d6..3bebdb9 100644
--- a/operations/common/gegl.c
+++ b/operations/common/gegl.c
@@ -52,8 +52,6 @@ attach (GeglOperation *operation)
 
 #include <stdio.h>
 
-static char *cached = NULL;
-
 static void
 prepare (GeglOperation *operation)
 {
@@ -63,7 +61,7 @@ prepare (GeglOperation *operation)
 
   gegl = operation->node;
 
-  if (!o->user_data || !g_str_equal (cached, o->user_data))
+  if (!o->user_data || !g_str_equal (o->user_data, o->string))
   {
     if (o->user_data)
       g_free (o->user_data);