Fix quoting when making derived mode docstring

* lisp/emacs-lisp/derived.el (derived-mode-make-docstring):
Nest regexp-quote inside format, not the reverse.
Problem reported by Artur Malabarba in:
http://lists.gnu.org/archive/html/emacs-devel/2015-06/msg00206.html

1 files changed, 4 insertions, 3 deletions

diff --git a/lisp/emacs-lisp/derived.el b/lisp/emacs-lisp/derived.el
index 75bd325d9db..52ff2aa99a2 100644
--- a/lisp/emacs-lisp/derived.el
+++ b/lisp/emacs-lisp/derived.el
@@ -331,9 +331,10 @@ which more-or-less shadow%s %s's corresponding table%s."
                         "\n\nThis mode "
                       (concat
                        "\n\nIn addition to any hooks its parent mode "
-                       (if (string-match (regexp-quote (format "[`‘]%s['’]"
-                                                               parent))
-                                         docstring) nil
+                       (if (string-match (format "[`‘]%s['’]"
+                                                 (regexp-quote parent))
+                                         docstring)
+                           nil
                          (format "`%s' " parent))
                        "might have run,\nthis mode "))
                     (format "runs the hook `%s'" hook)