CLJS-1420 - get-in behavior differs from Clojure by always deferring to the 3 arity fn

Reverts back to original reduce for 2 arity get-in

Author: rabidpraxis

src/main/cljs/cljs/core.cljs

@@ -4668,7 +4668,7 @@ reduces them without incurring seq initialization"
   {:added "1.2"
    :static true}
   ([m ks]
-     (get-in m ks nil))
+     (reduce get m ks))
   ([m ks not-found]
      (loop [sentinel lookup-sentinel
             m m

src/test/cljs/cljs/core_test.cljs

@@ -3111,6 +3111,15 @@
 (deftest test-cljs-1569
   (is (= (meta (with-meta (seq [1 2 3]) {:a 1})) {:a 1})))
 
+(deftest test-cljs-1420
+  (is (= :2-arity
+         (get-in
+           (reify
+             ILookup
+             (-lookup [o k] :2-arity)
+             (-lookup [o k not-found] :3-arity))
+           [:foo]))))
+
 
 (comment
   ;; ObjMap