Fix `magit-status-no-new-window` failing to open repos by symlink

`let`s `default-directory` instead of using the `directory` argument
of `magit-status`. This allows it to use it's normal directory
handling.

.emacs.d/init.el

@@ -480,10 +480,11 @@
   :init
   (defun magit-status-no-new-window (directory)
     (interactive "D")
-    (progn (let ((magit-display-buffer-function
-                 '(lambda (buffer)
-                   (display-buffer buffer '(display-buffer-same-window)))))
-              (magit-status directory)))))
+    (let ((magit-display-buffer-function
+           '(lambda (buffer)
+              (display-buffer buffer '(display-buffer-same-window))))
+          (default-directory directory))
+      (magit-status))))
 
 (use-package popwin :ensure
   :disabled