Patch Set 14: (3 inline comments)

Good and important work!

You should change the commit message. It should describe the whole change. Comments meant for review should go into the gerrit comments. Otherwise it is difficult for a new reviewer to understand the whole change.
I would find it useful to have the description of compatibility tests here (as in https://bugs.eclipse.org/bugs/show_bug.cgi?id=303925#c5).

Do you plan to add core.excludesfile? Regarding that I would however suggest to do that in a subsequent commit.

Please have a look at my inline comments.