Fix delete-duplicate-lines

* lisp/sort.el (delete-duplicate-lines): Delete duplicate
first line when operating backward (bug#23863).

diff --git a/lisp/sort.el b/lisp/sort.el
index 4d7311f1e510a0e4e17c86c099c2a4a93a4024a6..8bc71388ad5642c020e862dd2903c9b434521961 100644 (file)
--- a/lisp/sort.el
+++ b/lisp/sort.el
@@ -596,7 +596,7 @@ is non-nil, it also prints a message describing the number of deletions."
           (equal current-prefix-arg '(64))
           t)))
   (let ((lines (unless adjacent (make-hash-table :test 'equal)))
-       line prev-line
+       line prev-line first-line
        (count 0)
        (beg (copy-marker beg))
        (end (copy-marker end)))
@@ -604,8 +604,9 @@ is non-nil, it also prints a message describing the number of deletions."
       (goto-char (if reverse end beg))
       (if (and reverse (bolp)) (forward-char -1))
       (while (if reverse
-                (and (> (point) beg) (not (bobp)))
+                (not first-line)
               (and (< (point) end) (not (eobp))))
+       (setq first-line (and reverse (or (<= (point) beg) (bobp))))
        (setq line (buffer-substring-no-properties
                    (line-beginning-position) (line-end-position)))
         (if (and keep-blanks (string= "" line))