- PR/41321 - handle packages which generate multiple pkgnames from the same
  pkgdir - e.g. "py{25,26,27}-sqlite3-0nb2.tgz"
- Add support for pkg_summary.bz2 and pkg_summary.txt. Preferred order is now
  pkg_summary.bz2, pkg_summary.gz then pkg_summary.txt
- Drop support for old pkg_chk-summary file