Wrong icon on WP 4.0 open widgets

I noticed that on WP 4.0 the “+” icons on widget title bar becomes a “^” arrow when the widgets are expanded.

That happens because the CSS rules of you plugin:

.oomph-cloneable a.clone-widget::after {
content: "\f132";
}

is overridden by a WP core rule (in wp-admin/css/common.css):

.control-section.open .accordion-section-title:after, #customize-info.open .accordion-section-title:after, .nav-menus-php .menu-item-edit-active .item-edit:before, .widget.open .widget-top a.widget-action:after {
content: '\f142';
}

The following change should fix it:

.widget.open.oomph-cloneable a.clone-widget::after, .oomph-cloneable a.clone-widget::after {
content: "\f132";
}

https://wordpress.org/plugins/oomph-clone-widgets/