+ - speed up ssh tarball generation: No longer write indidividual user's ssh
+ authorized_keys to disk, only to read them later. Directly create a
+ TarInfo object without referring to any on-disk files.
+ - get rid of global state variable CurrentHost. This will enable upcoming
+ changes.
+ - UDLdap.py: make a cache for __getitem__() decisions.
+ - wrap cdbmake calls in eatmydata. Nothing else does any fsync stuff,
+ so doing it here just costs a lot.