vc-bzr.el (vc-bzr-checkin): Undo spurious `async' arg change.

lisp/vc-bzr.el

@@ -457,7 +457,7 @@ or a superior directory.")
   "Check FILE in to bzr with log message COMMENT.
 REV non-nil gets an error."
   (if rev (error "Can't check in a specific revision with bzr"))
-  (apply 'vc-bzr-command "commit" nil 'async
+  (apply 'vc-bzr-command "commit" nil 0
          files (cons "-m" (log-edit-extract-headers '(("Author" . "--author")
                                                       ("Fixes" . "--fixes"))
                                                     comment))))