Fix test

[Tieske]

Make tests more robust;

• prevent tests from hanging when failing,
• removed some ugly broken pipe errors,
• added retry for a time sensitive test (getting pid from file not yet written)

[thibaultcha]

I like this! tests need so much love! Thanks.

[subnetmarco]

The CLI has been rewritten in feat/invalidations, so we need to make sure this is still relevant with the new code.

[thibaultcha]

Well this touches the specs and

• I don't think they have been changed in invalidations
• If so, and if they are not relevant, then the person merging on rebasing invalidations is responsible for judging that and removing/adapting them as necessary.