This is related directly to JENKINS-44416

Technically it's not a bug I suppose, as the functionality works as described:

"Notice that you can set the Repository URL field to a Subversion repository root rather than just pointing to a tags dir (ie, you can set it to https://svn.jenkins-ci.org rather than https://svn.jenkins-ci.org/tags). In that case, if this repository root contains the trunk, branches and tags folders, then the dropdown will allow the user to pick the trunk, or a branch, or a tag."

Can this be changed so that the children are seen correctly in the following cases?

Where the repository root contains:

trunk (works, trivially, of course, so don't break it)

trunk, branches (the case I stumbled upon: doesn't work)

trunk, tags (not tested)

trunk, branches, tags (works, as advertised, thanks!)

This would match the user's expectation (mine that picking branches should not depend on the existance of tags. I have repositories that often have tags but no branches or branches and no tags. I don't see why it's better to require all three for the dropdown to allow the user to pick them.