Backport commit 5bdc97d55 from Emacs

Be consistent in spelling 'ok-if-already-exists'.
5bdc97d55df30f6af107ddd136901983a7e2706a
Paul Eggert
Sun Aug 13 11:55:12 2017 -0700

lisp/org-mobile.el

@@ -467,7 +467,7 @@ agenda view showing the flagged items."
 	  (make-directory target-dir 'parents))
 	(if org-mobile-use-encryption
 	    (org-mobile-encrypt-and-move file target-path)
-	  (copy-file file target-path 'ok-if-exists))
+	  (copy-file file target-path 'ok-if-already-exists))
 	(setq check (shell-command-to-string
 		     (concat (shell-quote-argument org-mobile-checksum-binary)
 			     " "
@@ -687,7 +687,7 @@ encryption program does not understand them."
   (let ((encfile (concat infile "_enc")))
     (org-mobile-encrypt-file infile encfile)
     (when outfile
-      (copy-file encfile outfile 'ok-if-exists)
+      (copy-file encfile outfile 'ok-if-already-exists)
       (delete-file encfile))))
 
 (defun org-mobile-encrypt-file (infile outfile)