[gegl] TIFF saved with bad height if buffer origin is non-zero

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

commit 97b4e887af2e8c755d9102fa0d886f978707d176
Author: Brian Stafford <contact brianstafford info>
Date:   Tue Mar 12 17:09:48 2019 +0000

    TIFF saved with bad height if buffer origin is non-zero
    
    Height of data exceeds TIFF headers by buffer y origin.
    Initial rows filled with garbage.

 operations/external/tiff-save.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/operations/external/tiff-save.c b/operations/external/tiff-save.c
index 82c82bbab..c63239204 100644
--- a/operations/external/tiff-save.c
+++ b/operations/external/tiff-save.c
@@ -344,9 +344,9 @@ save_contiguous(GeglOperation *operation,
           gegl_buffer_get(input, &tile, 1.0, format, buffer,
                           GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
 
-          for (row = y; row < y + tile_height; row++)
+          for (row = 0; row < tile_height; row++)
             {
-              guchar *tile_row = buffer + (bytes_per_row * (row - y));
+              guchar *tile_row = buffer + (bytes_per_row * row);
               gint written;
 
               written = TIFFWriteScanline(p->tiff, tile_row, row, 0);