Add customOmitClone helper.

lodash.js

@@ -2464,24 +2464,6 @@
       return shuffleSelf(copyArray(array));
     }
 
-    /**
-     * Used by `_.defaults` to customize its `_.assignIn` use.
-     *
-     * @private
-     * @param {*} objValue The destination value.
-     * @param {*} srcValue The source value.
-     * @param {string} key The key of the property to assign.
-     * @param {Object} object The parent object of `objValue`.
-     * @returns {*} Returns the value to assign.
-     */
-    function assignInDefaults(objValue, srcValue, key, object) {
-      if (objValue === undefined ||
-          (eq(objValue, objectProto[key]) && !hasOwnProperty.call(object, key))) {
-        return srcValue;
-      }
-      return objValue;
-    }
-
     /**
      * This function is like `assignValue` except that it doesn't assign
      * `undefined` values.
@@ -5606,6 +5588,63 @@
       return setWrapToString(setter(result, newData), func, bitmask);
     }
 
+    /**
+     * Used by `_.defaults` to customize its `_.assignIn` use to assign properties
+     * of source objects to the destination object for all destination properties
+     * that resolve to `undefined`.
+     *
+     * @private
+     * @param {*} objValue The destination value.
+     * @param {*} srcValue The source value.
+     * @param {string} key The key of the property to assign.
+     * @param {Object} object The parent object of `objValue`.
+     * @returns {*} Returns the value to assign.
+     */
+    function customDefaultsAssignIn(objValue, srcValue, key, object) {
+      if (objValue === undefined ||
+          (eq(objValue, objectProto[key]) && !hasOwnProperty.call(object, key))) {
+        return srcValue;
+      }
+      return objValue;
+    }
+
+    /**
+     * Used by `_.defaultsDeep` to customize its `_.merge` use to merge source
+     * objects into destination objects that are passed thru.
+     *
+     * @private
+     * @param {*} objValue The destination value.
+     * @param {*} srcValue The source value.
+     * @param {string} key The key of the property to merge.
+     * @param {Object} object The parent object of `objValue`.
+     * @param {Object} source The parent object of `srcValue`.
+     * @param {Object} [stack] Tracks traversed source values and their merged
+     *  counterparts.
+     * @returns {*} Returns the value to assign.
+     */
+    function customDefaultsMerge(objValue, srcValue, key, object, source, stack) {
+      if (isObject(objValue) && isObject(srcValue)) {
+        // Recursively merge objects and arrays (susceptible to call stack limits).
+        stack.set(srcValue, objValue);
+        baseMerge(objValue, srcValue, undefined, customDefaultsMerge, stack);
+        stack['delete'](srcValue);
+      }
+      return objValue;
+    }
+
+    /**
+     * Used by `_.omit` to customize its `_.cloneDeep` use to only clone plain
+     * objects.
+     *
+     * @private
+     * @param {*} value The value to inspect.
+     * @param {string} key The key of the property to inspect.
+     * @returns {*} Returns the uncloned value or `undefined` to defer cloning to `_.cloneDeep`.
+     */
+    function customOmitClone(value, key) {
+      return (key !== undefined && isPlainObject(value)) ? undefined : value;
+    }
+
     /**
      * A specialized version of `baseIsEqualDeep` for arrays with support for
      * partial deep comparisons.
@@ -6503,29 +6542,6 @@
       return data;
     }
 
-    /**
-     * Used by `_.defaultsDeep` to customize its `_.merge` use.
-     *
-     * @private
-     * @param {*} objValue The destination value.
-     * @param {*} srcValue The source value.
-     * @param {string} key The key of the property to merge.
-     * @param {Object} object The parent object of `objValue`.
-     * @param {Object} source The parent object of `srcValue`.
-     * @param {Object} [stack] Tracks traversed source values and their merged
-     *  counterparts.
-     * @returns {*} Returns the value to assign.
-     */
-    function mergeDefaults(objValue, srcValue, key, object, source, stack) {
-      if (isObject(objValue) && isObject(srcValue)) {
-        // Recursively merge objects and arrays (susceptible to call stack limits).
-        stack.set(srcValue, objValue);
-        baseMerge(objValue, srcValue, undefined, mergeDefaults, stack);
-        stack['delete'](srcValue);
-      }
-      return objValue;
-    }
-
     /**
      * This function is like
      * [`Object.keys`](http://ecma-international.org/ecma-262/7.0/#sec-object.keys)
@@ -12781,7 +12797,7 @@
      * // => { 'a': 1, 'b': 2 }
      */
     var defaults = baseRest(function(args) {
-      args.push(undefined, assignInDefaults);
+      args.push(undefined, customDefaultsAssignIn);
       return apply(assignInWith, undefined, args);
     });
 
@@ -12805,7 +12821,7 @@
      * // => { 'a': { 'b': 2, 'c': 3 } }
      */
     var defaultsDeep = baseRest(function(args) {
-      args.push(undefined, mergeDefaults);
+      args.push(undefined, customDefaultsMerge);
       return apply(mergeWith, undefined, args);
     });
 
@@ -13467,7 +13483,7 @@
       });
       copyObject(object, getAllKeysIn(object), result);
       if (isDeep) {
-        result = baseClone(result, CLONE_DEEP_FLAG | CLONE_FLAT_FLAG | CLONE_SYMBOLS_FLAG);
+        result = baseClone(result, CLONE_DEEP_FLAG | CLONE_FLAT_FLAG | CLONE_SYMBOLS_FLAG, customOmitClone);
       }
       var length = paths.length;
       while (length--) {
@@ -14735,9 +14751,9 @@
         options = undefined;
       }
       string = toString(string);
-      options = assignInWith({}, options, settings, assignInDefaults);
+      options = assignInWith({}, options, settings, customDefaultsAssignIn);
 
-      var imports = assignInWith({}, options.imports, settings.imports, assignInDefaults),
+      var imports = assignInWith({}, options.imports, settings.imports, customDefaultsAssignIn),
           importsKeys = keys(imports),
           importsValues = baseValues(imports, importsKeys);