Empty "tag" definition for Subversion Repos, overrides the trunk RegExp

The following in the svn repo spec:

<tag regex="" name="" logical=""/>

will mean that trunk will never be matched!

See screenshot attached.
Adding anything to the <tag regex=""/> e.g. regex="xxx" will allow trunk to match correctly.

This is counter-intuitive if you wished to exclude all your tags from FE indexing, say.