[gegl] buffer: fix gegl_buffer_copy() for shifted buffers

[N/A <ell src gnome org>]

commit 5c741a6951e0d9f68e70ab339cc57d22b3e678df
Author: Ell <ell_se yahoo com>
Date:   Mon Dec 11 10:05:54 2017 -0500

    buffer: fix gegl_buffer_copy() for shifted buffers

 gegl/buffer/gegl-buffer-access.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-access.c b/gegl/buffer/gegl-buffer-access.c
index acb8699..0f01c97 100644
--- a/gegl/buffer/gegl-buffer-access.c
+++ b/gegl/buffer/gegl-buffer-access.c
@@ -1703,8 +1703,8 @@ gegl_buffer_copy (GeglBuffer          *src,
                 gint src_x, src_y;
                 gint stx, sty, dtx, dty;
 
-                src_x = dst_x - (dst_rect->x - src_rect->x) + src->shift_x;
-                src_y = dst_y - (dst_rect->y - src_rect->y) + src->shift_y;
+                src_x = dst_x + (src_rect->x - dst_rect->x) + (src->shift_x - dst->shift_x);
+                src_y = dst_y + (src_rect->y - dst_rect->y) + (src->shift_y - dst->shift_y);
 
                 stx = gegl_tile_indice (src_x, tile_width);
                 sty = gegl_tile_indice (src_y, tile_height);