Hi,

Since months now there are a lot of random failure on the CI making it
hard to work.

There is different kind of failures:
- Network problems
- Failing tests
- Incomprehensible problems

Now I don't see much failure due to Network. I suppose the Inria
infrastructure improved.

Failing tests were corrected those past months and we see less and less
of them.

Now the big problem are the incomprehensible crashes such as "The
workspace was not found" or "FileDoesNotExistException" or "pharo-vm/ is
already present".

We just found the problem :)

During the validation of the Bootstrap multiple tests are launched on
OSX/Windows/linux in parallel. Each task is on a different slave of the
Jenkins. But, apparently we discovered that two slaves could have the
same disk. Usually it does not cause any trouble since a job is only run
by one slave. But in this particular case, two slaves can be used by the
same job and mess with the resources of each other.