Can't select new default theme when Documentation theme is global

If the Documentation Theme is your global look-and-feel it is not possible to select the new default theme for an individual space.

Only work around would be to select the default theme as default, and set the documentation theme manually to all spaces, but this is a manual and painful job.

I would expect to be able to select the new default theme for an individual space, even if the Documentation theme is default. This would make te migration a whole lot easier