Bug 20660: Return date override affects debarments in AddReturn

Bug 20660: Return date override affects debarments in AddReturn

Re-did the patch to follow best practices.

TEST PLAN:
0. Apply first patch only
1. prove t/db_dependent/Circulation.t
2. Apply second patch
3. prove t/db_dependent/Circulation.t

prove should fail the first time and pass the second time.

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>