Site plugin install the wrong site.xml descriptor in local repository since 2.0-beta-6

I just tryed to build an old project and I found that it was no more working.
After investigating this I see that now maven ends up installing a wrong site.xml (the one from the parent) instead of the right one.

I attach a simple multimodule project to reproduce this issue.

If you run an "mvn install site" from the root you see that in the com.example/project/1.0-SNAPSHOT folder the project-1.0-SNAPSHOT-site.xml is instead the site.xml for the "parent" artifact and not the one that I have in the "project" artifact.

This seems a critical issue.

Try uncommenting the pluginManagement where I declare site 2.0-beta-5 and everything will work fine!
I don't know how to setup the environment to be able to create an it test to submit to the site plugin developers, hope the test is good enough.