Now jQuery.extend (deep copy) doesn't allow to extend custom object by server response (plain object from JSON)

http://jsfiddle.net/C4duF/

On deep copy jQuery requires both property values to be plain objects to proceed recursively, otherwise it replaces value in target.

Could this be changed to requirement when target could be any object (not only plain) but other side must be plain?

// Recurse if we're merging plain objects or arrays
if ( deep && copy && ( jQuery.isPlainObject(copy) || (copyIsArray = jQuery.isArray(copy)) ) ) {
	if ( copyIsArray ) {
		copyIsArray = false;
		clone = src && jQuery.isArray(src) ? src : [];

	} else {
		// CHNAGE FROM:
		//clone = src && jQuery.isPlainObject(src) ? src : {};
		// CHNAGE TO:
		clone = !src || jQuery.type(src) !== "object" || src.nodeType || jQuery.isWindow( src ) ? {} : src;
	}

	// Never move original objects, clone them
	target[ name ] = jQuery.extend( deep, clone, copy );

// Don't bring in undefined values
} else if ( copy !== undefined ) {
	target[ name ] = copy;
}