When the tee filter excludes some of the queries mandatory queries are always duplicated. The COM_FIELD_LIST packets were duplicated even though they don't change the state of the session or create or modify data. This leads to a hang when a USE <db> is send from the command line.
Steps to reproduce:
- Configure two services, one with a tee filter which feeds to the other service.
- Add match=insert for the tee filter
- Execute USE test