Small fix

* lisp/org.el (org-clone-subtree-with-time-shift): Handle nil shift
  case.

lisp/org.el

@@ -8999,7 +8999,8 @@ with the original repeater."
     (let* ((end (point))
 	   (template (buffer-substring beg end))
 	   (shift-n (and doshift (string-to-number (match-string 1 shift))))
-	   (shift-what (pcase (match-string 2 shift)
+	   (shift-what (pcase (and doshift (match-string 2 shift))
+			 (`nil nil)
 			 ("d" 'day)
 			 ("w" (setq shift-n (* 7 shift-n)) 'day)
 			 ("m" 'month)