magit-status-parent.el

(defun magit-status-parent ()
  "Open the magit status of a parent git repository. Useful for
dealing with submodules. Suggest binding to SPC g p for Spacemacs.

  (spacemacs/set-leader-keys \"gp\" 'magit-status-parent)
"
  (interactive)
  (let* ((child-directory (magit-toplevel default-directory))
         (parent-directory (and child-directory
                                (magit-toplevel (file-name-directory
                                                 (directory-file-name child-directory))))))
    (if (null child-directory)
        (user-error "No child git repository in %s." default-directory)
      (if (null parent-directory)
          (user-error "No parent git repository in %s." child-directory)
        (magit-status parent-directory)))))