ACLs on /target/ while installation causing trouble

[Ian Kelling]

For anyone else hitting this, also worth noting that basefiles
generated on a system with messed up acls can have
bad acls built in to them and they will need to be
fixed / recreated in addition to putting a new tar in the
nfsroot.

Alternate way of getting new tar that I used:
On the fai server:

cat >/etc/fai/apt/preferences <<'EOF'
Package: tar
Pin: release a=jessie-backports
Pin-Priority: 500
EOF

tee -a >/etc/fai/apt/sources.list <<'EOF'
deb http://ftp.debian.org/debian jessie-backports main
EOF

then regenerated the nfsroot.