I don't know if this is an issue, since I've guessing it only happens in release candidates, but I noticed in 2.0.2-rc3 that there are 3 "undefined offset" errors when you go to admin.

It turns out they're caused by LeftAndMain::CMSVersion - the regular expressions don't allow for the /rc/ in the version string.

If you put "(?:\/rc)?" in each of the 3 regexes like this: "/sapphire\/(? ?:branches)|(?:tags))(?:\/rc)?\/([A-Za-z0-9._-]+)\/silverstripe_version/"

it fixes the errors