po-mode.el: po-check-file-header always inserts header in Emacs 23

[Sven Joachim]

Hi,

in current Emacs CVS, loading a PO file always inserts an extra header
at the beginning of the buffer, even if there is already one.  I tracked
this misbehavior down to a changed semantic of the previous-line (and
next-line) function in Emacs, which by default now moves by display
lines:

,----[ C-h f previous-line ]
| previous-line is an interactive compiled Lisp function in `simple.el'.
| 
| It is bound to <up>, C-p.
| 
| (previous-line &optional arg try-vscroll)
| 
| Move cursor vertically up arg lines.
| Interactively, vscroll tall lines if `auto-window-vscroll' is enabled.
| If there is no character in the target line exactly over the current column,
| the cursor is positioned after the character in that line which spans this
| column, or at the end of the line if it is not long enough.
| 
| If the variable `line-move-visual' is non-nil, this command moves
| by display lines.  Otherwise, it moves by buffer lines, without
| taking variable-width characters or continued lines into account.
| 
| The command C-x C-n can be used to create
| a semipermanent goal column for this command.
| Then instead of trying to move exactly vertically (or as close as possible),
| this command moves to the specified goal column (or as close as possible).
| The goal column is stored in the variable `goal-column', which is nil
| when there is no goal column.
| 
| If you are thinking of using this in a Lisp program, consider using
| `forward-line' with a negative argument instead.  It is usually easier
| to use and more reliable (no dependence on goal column, etc.).
`----

The statement in the last paragraph is also true in Emacs 22 and 21, so
the following patch seems to be safe:

2008-08-13  Sven Joachim  <address@hidden>

        * po-mode.el (po-check-file-header): Use forward-line with
        negative argument instead of previous-line.
        (po-add-attribute): Use forward-line instead of next-line.

--8<---------------cut here---------------start------------->8---
--- po-mode.el.~1.42.~  2008-05-25 13:18:51.000000000 +0200
+++ po-mode.el  2008-08-13 19:45:38.000000000 +0200
@@ -1342,7 +1342,7 @@
             (progn
               ;; There is at least one entry.
               (goto-char (match-beginning 0))
-              (previous-line 1)
+              (forward-line -1)
               (setq end-of-header (match-end 0))
               (if (looking-at "msgid \"\"\n")
                   ;; There is indeed a PO file header.
@@ -1352,7 +1352,7 @@
                     ;; This is an oldish header.  Replace it all.
                     (goto-char end-of-header)
                     (while (> (point) (point-min))
-                      (previous-line 1)
+                      (forward-line -1)
                       (insert "#~ ")
                       (beginning-of-line))
                     (beginning-of-line)
@@ -1498,7 +1498,7 @@
               (insert ", " name)))
         (skip-chars-forward "\n")
         (while (eq (following-char) ?#)
-          (next-line 1))
+          (forward-line 1))
         (insert "#, " name "\n")))))
 
 (defun po-delete-attribute (name)
--8<---------------cut here---------------end--------------->8---

Cheers,
       Sven