Enable merge of authority records to do the right thing

Enable merge of authority records to do the right thing

The target and source authority record was flipped, causing
the update to fail. In reconsidering this function, it is not
necessary to change the contents of the source authority record
just to propagate the content of the target authority record
to any linked bibliographic records.

Instead, take the approach of updating the ID of the controlled
field in the bib record, then temporarily set "reingest on same
MARC" to TRUE and update the target authority record by setting
deleted = FALSE (which propagates the "changes" to the linked
bib records), then set "reingest on same MARC" flag back to its
original value.

This has the bonus of actually working.

git-svn-id: svn://svn.open-ils.org/ILS/trunk@18567 dcc99617-32d9-48b4-a31d-7c20da2025e4