Item12368: Assign a default for the system group

This was causing undefined variable in lc errors on some versions of
windows. I was unable to recreate the failure, but this should fix it,

git-svn-id: http://svn.foswiki.org/branches/Release01x01/core@16458 0b4bb1d4-4e5a-0410-9cc4-b2b747904278