Create session under "Sessions" tab does not delete older session links

[powermukisa]

Steps:

• On the sessions tab, create a new session for a game
• After the session is created, return to the sessions tab and Delete the session
• Create another session for the same game

Results:

• Older sessions are still shown under the Single-use links (see screeshot below)
• Session-wide link is not valid

Expected:

• Older sessions should be deleted
• Session wide link should be valid.

Note: does not happen when you archive instead of deleting a session.

[oTree-org]

Good find! I have found the cause (sqlite does not enforce FK constraints by default) and will publish a fix soon.