Travis failures with Postgres tests

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• Problem/bug report.
• Feature request.
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Description

Travis builds are failing semi randomly now that we're testing against Postgres. Tests pass when rerun manually. I suspect a database contention or cleaning issue, but I haven't reproduced it reliably yet.

Commencez par examiner la configuration de Travis et la configuration des tests Postgres, puis relancez la suite en échec afin de comparer les échecs intermittents avec les relances manuelles. Étudiez la contention de la base de données ou le comportement de nettoyage signalé ; le travail est terminé lorsque les tests Postgres passent systématiquement dans Travis.