Bug 9609: Rebuilding zebra reports double number of exported records.

Bug 9609: Rebuilding zebra reports double number of exported records.

Test plan:
Clear the zebra queue (run rebuild). Update one biblio.
Rebuild zebra (again) with -z. Check zebra log: note 2 exported records.
Now apply patch, and repeat: You will see 1 exported record.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works as described.
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>