Members can give references for registrations that start after their membership ends

One-sentence description

Members can give references for registrations that start after their membership ends

Current behaviour / Reproducing the bug

1. Create a member with a membership that ends on 31-08-2019
2. Start a registration for the next lecture year (1 Sept)
3. Use the previously created member to create a reference
4. Works

Expected behaviour

1. Create a member with a membership that ends on 31-08-2019
2. Start a registration for the next lecture year (1 Sept)
3. Use the previously created member to create a reference
4. Does not work