plone.rest vulnerable to Denial of Service when ++api++ is used many times

plone.rest allows users to use HTTP verbs such as GET, POST, PUT, DELETE, etc. in Plone. Starting in the 2.x branch and prior to versions 2.0.1 and 3.0.1, when the `++api++` traverser is accidentally used multiple times in a url, handling it takes increasingly longer, making the server less responsive. Patches are available in `plone.rest` 2.0.1 and 3.0.1. Series 1.x is not affected. As a workaround, one may redirect `/++api++/++api++` to `/++api++` in one's frontend web server (nginx, Apache).