Newest Plone 5.2: unable to create a Plone site via the ZMI

Plone installation as created a few minutes ago by a current buildout.coredev: the creation of a Plone site via the ZMI fails due to

See for a fix to the old patch that added the "add plone site" button. You can currently only create a site from the frontpage at localhost:8080

Thank you for your response.

I have created Plone sites by manually fixing the broken action urls via the "firefox" "inspector" (thereby verifying that the only problem is the broken ZMI add).