Cannot run two CI's in parallel
We're presently facing an issue that, from time to time, tests on the MacOS CI will fail, after hanging for 1h30.
The problem seems to be that some of the tests are probably communicating to other processes using the same network/IO infrastructure (e.g. port number).
Here is an example dead-lock:
MacOS + python 27: https://gitlab.idiap.ch/beat/beat.core/-/jobs/133089 MacOS + python 36: https://gitlab.idiap.ch/beat/beat.core/-/jobs/133090