CLJ-1870: don't destroy defmulti metadata on reload

Signed-off-by: Stuart Halloway <stu@cognitect.com>

Author: bronsa

src/clj/clojure/core.clj

@@ -1757,7 +1757,8 @@
                       m)
         m           (if (meta mm-name)
                       (conj (meta mm-name) m)
-                      m)]
+                      m)
+        mm-name (with-meta mm-name m)]
     (when (= (count options) 1)
       (throw (Exception. "The syntax for defmulti has changed. Example: (defmulti name dispatch-fn :default dispatch-value)")))
     (let [options   (apply hash-map options)
@@ -1766,7 +1767,7 @@
       (check-valid-options options :default :hierarchy)
       `(let [v# (def ~mm-name)]
          (when-not (and (.hasRoot v#) (instance? clojure.lang.MultiFn (deref v#)))
-           (def ~(with-meta mm-name m)
+           (def ~mm-name
                 (new clojure.lang.MultiFn ~(name mm-name) ~dispatch-fn ~default ~hierarchy)))))))
 
 (defmacro defmethod