Use floor of mtime instead of rounding for thumb property

This seems to be the correct thing to do, at least more in line with
what at least one other implementation does.  Anything using
gnome-desktop [0] effectively does the same, as
gnome_desktop_thumbnail_is_valid applies atol(3) to mtime for
comparison and time_t on GNU/Linux is a signed int.
[0] https://git.gnome.org/browse/gnome-desktop/
* lisp/image-dired.el (image-dired-create-thumb): Use floor here.

diff --git a/lisp/image-dired.el b/lisp/image-dired.el
index 96570a503f82e9a9a8a49fc29b8ab04836e83ad6..dd0c5b512e7b0ac6fa1a1d825d134d9f68255946 100644 (file)
--- a/lisp/image-dired.el
+++ b/lisp/image-dired.el
@@ -646,8 +646,7 @@ DIMENSION should be either the symbol 'width or 'height."
    'image-dired-cmd-create-thumbnail-program)
   (let* ((width (int-to-string (image-dired-thumb-size 'width)))
          (height (int-to-string (image-dired-thumb-size 'height)))
-         (modif-time (format "%.0f" (float-time (nth 5 (file-attributes
-                                                        original-file)))))
+         (modif-time (floor (float-time (nth 5 (file-attributes original-file)))))
          (thumbnail-nq8-file (replace-regexp-in-string ".png\\'" "-nq8.png"
                                                        thumbnail-file))
          (command