[gimp/gimp-2-10] plug-ins: in file-tiff, don't leak image when not saving layers

[Ell <ell src gnome org>]

commit fce4e98097f96c1ccae7c93f5efa980043399de9
Author: Ell <ell_se yahoo com>
Date:   Mon Jun 3 12:36:36 2019 -0400

    plug-ins: in file-tiff, don't leak image when not saving layers
    
    In file-tiff, when not saving layers, avoid duplicating the image
    to create the merged version if it's already been duplicated, and
    make sure to delete the duplicated image otherwise.
    
    (cherry picked from commit 8831ef2ea099c2224102105a8148c4c0a9687a11)

 plug-ins/file-tiff/file-tiff.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/plug-ins/file-tiff/file-tiff.c b/plug-ins/file-tiff/file-tiff.c
index dbaa6a153d..f327e9ddb9 100644
--- a/plug-ins/file-tiff/file-tiff.c
+++ b/plug-ins/file-tiff/file-tiff.c
@@ -478,8 +478,13 @@ run (const gchar      *name,
             {
               gint32 transp;
 
-              /* FIXME: Do we have to update drawable, too? */
-              image = gimp_image_duplicate (image);
+              if (export != GIMP_EXPORT_EXPORT)
+                {
+                  image    = gimp_image_duplicate (image);
+                  drawable = gimp_image_get_active_layer (image);
+
+                  export = GIMP_EXPORT_EXPORT;
+                }
 
               /* borrowed from ./libgimp/gimpexport.c:export_merge()
                * this makes sure that the exported file size is correct. */