Since the upgrade to Kernel 4.15, I see a much increased number of 'stalled'
OBS workers.

The stall happens in various packages, most prominently, llvm5, ceph,
libreoffice and java-9-openjdk. Most of the time, they are 'fine' after several
attempts.

There seems to be one package reliably reproducing it: tar on i586

https://build.opensuse.org/package/live_build_log/openSUSE:Factory/tar/standard/i586

I'm CCing Adrian (OBS Admin) here, as he will likely be the only person that
can provide traces from the VM, at the time this happens.