Concurrent bucket deletion across multiple filer replicas races on the
per-bucket DROP TABLE. The first replica drops the table; the rest hit
an undefined-table error (postgres 42P01, mysql 1051) which propagates
out of DeleteFolderChildren and panics the filer. On restart the same
pending DROP re-runs and the filer crash-loops.
Make the drop idempotent. Same defect class in all SQL backends, so fix
postgres, postgres2, mysql, mysql2, and sqlite together.
Chris Lu
Chris Lu
陈杨文