- re-instate v4 directory cleanup (bz# 193832 again).
    - backout master map lookup changes made to beta3.
    - change default master map from /etc/auto.master to auto.master so that we
        always use nsswitch to locate master map.
    - change default installed master map to include "+auto.master" to pickup
        NIS master map (all bz# 193831 again).