Clear func in function created by _.before without requiring an additional call. [closes #1088]

lodash.src.js

@@ -7375,7 +7375,8 @@
       return function() {
         if (--n > 0) {
           result = func.apply(this, arguments);
-        } else {
+        }
+        if (n <= 1) {
           func = null;
         }
         return result;