org-clock.el: Fix bug in `org-clock-timestamps-change'.

lisp/org-clock.el

@@ -1426,38 +1426,39 @@ If there is no running clock, throw an error, unless FAIL-QUIETLY is set."
   "Change CLOCK timestamps synchronously at cursor.
 UPDOWN tells whether to change 'up or 'down."
   (setq org-ts-what nil)
-  (let ((tschange (if (eq updown 'up) 'org-timestamp-up
-		    'org-timestamp-down))
-	ts1 begts1 ts2 begts2 updatets1 tdiff)
-    (save-excursion
-      (move-beginning-of-line 1)
-      (re-search-forward org-ts-regexp3 nil t)
-      (setq ts1 (match-string 0) begts1 (match-beginning 0))
-      (when (re-search-forward org-ts-regexp3 nil t)
-	(setq ts2 (match-string 0) begts2 (match-beginning 0))))
-    ;; Are we on the second timestamp?
-    (if (<= begts2 (point)) (setq updatets1 t))
-    (if (not ts2)
-	;; fall back on org-timestamp-up if there is only one
+  (when (org-at-timestamp-p t)
+    (let ((tschange (if (eq updown 'up) 'org-timestamp-up
+		      'org-timestamp-down))
+	  ts1 begts1 ts2 begts2 updatets1 tdiff)
+      (save-excursion
+	(move-beginning-of-line 1)
+	(re-search-forward org-ts-regexp3 nil t)
+	(setq ts1 (match-string 0) begts1 (match-beginning 0))
+	(when (re-search-forward org-ts-regexp3 nil t)
+	  (setq ts2 (match-string 0) begts2 (match-beginning 0))))
+      ;; Are we on the second timestamp?
+      (if (<= begts2 (point)) (setq updatets1 t))
+      (if (not ts2)
+	  ;; fall back on org-timestamp-up if there is only one
+	  (funcall tschange)
+	;; setq this so that (boundp 'org-ts-what is non-nil)
 	(funcall tschange)
-      ;; setq this so that (boundp 'org-ts-what is non-nil)
-      (funcall tschange)
-      (let ((ts (if updatets1 ts2 ts1))
-	    (begts (if updatets1 begts1 begts2)))
-	(setq tdiff
-	      (subtract-time
-	       (org-time-string-to-time org-last-changed-timestamp)
-	       (org-time-string-to-time ts)))
-	(save-excursion
-	  (goto-char begts)
-	  (org-timestamp-change
-	   (round (/ (org-float-time tdiff)
-		     (cond ((eq org-ts-what 'minute) 60)
-			   ((eq org-ts-what 'hour) 3600)
-			   ((eq org-ts-what 'day) (* 24 3600))
-			   ((eq org-ts-what 'month) (* 24 3600 31))
-			   ((eq org-ts-what 'year) (* 24 3600 365.2)))))
-	   org-ts-what 'updown))))))
+	(let ((ts (if updatets1 ts2 ts1))
+	      (begts (if updatets1 begts1 begts2)))
+	  (setq tdiff
+		(subtract-time
+		 (org-time-string-to-time org-last-changed-timestamp)
+		 (org-time-string-to-time ts)))
+	  (save-excursion
+	    (goto-char begts)
+	    (org-timestamp-change
+	     (round (/ (org-float-time tdiff)
+		       (cond ((eq org-ts-what 'minute) 60)
+			     ((eq org-ts-what 'hour) 3600)
+			     ((eq org-ts-what 'day) (* 24 3600))
+			     ((eq org-ts-what 'month) (* 24 3600 31))
+			     ((eq org-ts-what 'year) (* 24 3600 365.2)))))
+	     org-ts-what 'updown)))))))
 
 (defun org-clock-cancel ()
   "Cancel the running clock by removing the start timestamp."