Start magit or monky depending on repository found in buffer-local working directory.

gistfile1.el

(defun process-exit-code-and-output (program &rest args)
  "Run PROGRAM with ARGS and return the exit code and output in a list."
  (with-temp-buffer
    (list (apply 'call-process program nil (current-buffer) nil args)
          (buffer-string))))

(defun magit-or-monky-status ()
  "Call `magit-status' or `monky-status' depending on whether a
git or hg repository is found in the buffer-local working dir."
  (interactive)
  (cond
   ((eq (car (process-exit-code-and-output "hg" "status")) 0)
    (monky-status))
   ((eq (car (process-exit-code-and-output "git" "status")) 0)
    (call-interactively 'magit-status))
   (t (message "No hg or git repository found at %s" default-directory))))