Database migration nukes episode table

[rg9400]

Describe the bug
This database migration is bad. It removes the entire episode table, causing Bazarr to have to reindex the full list.

To Reproduce

1. Get a Bazarr version running with database version 30f37e2e15e1 and episode histories
2. Update Bazarr to the latest nightly version, so database version 452dd0f0b578 and check the episode table, verify it is all empty

Expected behavior
Database migrations should not nuke the episode table

Software (please complete the following information):

• Bazarr: [e.g. v 0.6.1] 1.4.3-beta.32

[morpheus65535]

In the last migration, we do some cleanup of an old left over column that have been recreated under a new name since then (alternativeTitle from table_shows) and that is causing issue while migrating to postgresql. This removal of column requires, under sqlite, to recreate the table under a temporary name, delete the old table and rename the new to the old name.

Unfortunately, the side effect of the old table deletion is that there's a ForeignKey constraint that cascade this deletion in table_episodes and, consequently, in table_history and table_blacklist.

I'll try to see if I can make alembic disable ForeignKey constraints before trying to migrate schema.

[morpheus65535]

Should be fixed in upcoming beta. Can you test and confirm please. I haven't been able to reproduce on my side with this fix. Thanks for reporting BTW!

[rg9400]

This issue seems resolved with the latest migration fix!

[morpheus65535]

Thanks!