"[/] @group = rw" not working after upgrade to SVN 1.13

After upgrading Ubuntu from 18.04 to 20.04, which includes the upgrade of Subversion from 1.9 to 1.13, the following setup no longer works, but according to the docs, the [/] approach should still be working.

Example illustrating the bug - no access for group "unlimited" to repository "repo1":

[groups]
unlimited = user1, user2

[/]
@unlimited = rw

[repo1:/]
user3 = rw

In this example, user1 and user2 do not have access to repo1. This was working in SVN 1.9 and I could not find anything in the docs that this would have been removed on the way to 1.13.

If I change the line "@unlimited = rw" to "* = r", then all users get read access as documented, meaning that the [/] definition is still applied to all repository-specific definitions.

The @unlimited group gets access to repo1 if I add that group explicitly to the [repo1:/] section. However, this is only a workaround and requires quite some effort if you have a high number of repositories.