* .dir-locals.el (magit-branch-adjust-remote-upstream-alist): New.

.dir-locals.el

 ((nil . ((whitespace-action auto-cleanup)
 	 (whitespace-style face empty trailing lines-tail)
 	 (require-final-newline . t)
-	 (mode . global-whitespace)))
+	 (mode . global-whitespace)
+         (magit-branch-adjust-remote-upstream-alist ("origin/next" . "/"))))
  (c++-mode . ((c-default-style . "gnu")
 	      (indent-tab-mode . t)
 	      (tab-width . 8)