Using switchtheme changes default template for anonymous users to garland.

Hi

I was just trying out the module and noticed this bug.

How to test:

1. I have a custom theme as default. with Garland disabled.
2. Activate switchtheme.
3. Activate the switchtheme block. (this also kicked me to default theme, but this can be changes,)
4. Change theme to something else.
5. log out. The logged out theme will be Garland, but it should be the previous default.
6. Log back in go to theme administration - Garland is checked as default theme (for me the active checkbox was still unticked...)