render="@form" with Omnifaces 2.0 and Richfaces 4.5 not working

Question

We're using a <a4j:commandLink ... /> with an action and render="@form". Since we've upgraded to Omnifaces 2.0 the action won't be invoked unless we replace @form with @this or an explicit id. The bean providing the action method is annotated with @javax.faces.view.ViewScoped.

Before with Omnifaces 1.8.1 it has worked well.

(We're using Java 8, JSF 2.2.6, Richfaces 4.5 and Wildfly 8.)

<a4j:commandLink id="#{cc.attrs.buttonId}"
               action="#{cc.attrs.action}"
               oncomplete="#{cc.attrs.oncomplete}"
               onbegin="#{cc.attrs.onbegin}"
               render="contentForm:contentSaveHandler contentToolbar @form"
               execute="@this">

    <h:outputText value="Test" />
</a4j:commandLink>

If I change @form to @this it works.