Travis failures with Postgres tests

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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.

まず Travis の設定と Postgres のテスト設定を調べ、次に失敗しているテストスイートを再実行して、一時的な失敗と手動での再実行結果を比較します。報告されているデータベースの競合またはクリーンアップ動作を調査します。Travis で Postgres のテストが安定して通過すれば完了です。