Group Calendar doesn't maintain Group Theme

I found that when, after specifying a specific theme for a group, that the group calendar page doesn't respect the group specific theme (it reverts back to the site default). I think this is a bug because all group specific pages should honor the chosen group theme (especially because this has implications for blocks that are only visible for a specific group). I've included a patch for review which makes the group calendar page keep the group theme when viewed.

Note: I'm not sure how to change the Group Calendar title that comes with it (i.e. to alter its appearance), it didn't seem to be generated by any of the og modules (og calendar in particular) - perhaps it's something that the event module generates. I'll look into that when I have time.