Bug 14597: Reverting a batch where a record overlaid is now deleted record will fail

Bug 14597: Reverting a batch where a record overlaid is now deleted record will fail

If batch of records is used to overlay existing records, and one of
those records is deleted, any attempt to revert this batch will fail.

The unanimous consensus is that deleted records should stay deleted (
 https://lists.katipo.co.nz/public/koha/2015-June/043048.html ).

Test Plan:
1) Import a batch of records
2) Import the same batch again, using ISBN as a matcher for overlay
3) Find a record that overlayed a previous record and delete it
   ( the match type will be "match applied" and there will be a link in
     "match details" )
4) Attempt to revert the second batch ( that overlayed the first )
5) The progress will stop at some point and never complete
6) Apply this patch
7) Attempt to revert the second batch again
8) This time it should succeed!

Signed-off-by: Do, Tam T <tdo@albright.edu>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>