support for fish shell

[gour]

Hello,

I'm using fish as my default shell and e.g. 'build' command fails due to:

(defun build-site ()
  "Build the site."
  (interactive)
  (let ((command (format
                  "cd %s && %s build &"
                  blog-admin-backend-path executable)))
    (-with-venv
(shell-command command))))

since fish shell needs:

cd %s; and build &

Any idea how blog-admin could be extended to cover fish shell?