Test runner should not die because of any RPC-related failure.
Also, print a nice traceback of the error.

Also, don't name custom log files with a leading dot in partition's root.
This is reserved to supervisord logfiles. Follow (somewhat) the FHS and
put log files in testrunner partition's /var/log.

Original implementation was defining it globally, and applying it on the
first repository list entry.

between to test suite launch, it is not needed to keep
supervidor running. This allows to save memory usage

This will allows to use it for several different external method
calls