Comment 1 for bug 1560344

Btw, http://refspecs.linuxfoundation.org/FHS_3.0/fhs-3.0.html mentions:
> 5.5. /var/cache : Application cache data
> ... The application must always be able to recover from manual deletion of these files ...

which does not correspond to the way we're using that directory, so moving to /run/ltsp is more appropriate.