Fix bug https://trac.macports.org/ticket/11637: livecheck incorrectly assumed that master_sites was set.
Fix bug https://trac.macports.org/ticket/11637:
livecheck incorrectly assumed that master_sites was set.

git-svn-id: 620571fa9b4bd0cbce9a0cf901e91ef896adbf27@23329 d073be05-634f-4543-b044-5fe20cf6d1d6

danchr/macports-base,macports/macports-base,macports/macports-base,neverpanic/macports-base,neverpanic/macports-base,danchr/macports-base