Fix/h2oheavyoil

This is an updated version of !722 (closed) with a manual cherry-pick of a part of 993d4801.

The 3pwateroil test passes for me now and produces the same amount of timesteps as on buildbot on my machine now. It will probably still fail on other machines. Nevertheless at least I get the same solution running it on 2 different machines.

Closes !722 (closed)