[Koha-devel] link_bibs_to_authorities.pl can corrupt records

[Paul]

Bug 5683 (link_bibs_to_authorities.pl can corrupt records) was signed off 
some months ago, but is perhaps a little too cryptic for me to follow in 
detail.  Can someone help? As far as I can see, without remedial action, 
this is catastrophic.

Following difficulties we have had migrating 3.2 to 3.6.1, someone on the 
users mailing list suggested we should run link_bibs_to_authorities.pl -- 
(db has ~10k authorities and ~15k biblios) -- so I did just that, and have 
APPARENTLY DEMOLISHED *EVERY* LINK IN THE DB.  From my notes:

paul at nelson:/usr/share/koha$ ./bin/link_bibs_to_authorities.pl

Bib authority heading linking report
------------------------------------
Number of bibs checked:       14911
Number of bibs modified:      14886
Number of bibs with errors:   0

but - the staff interface no longer correctly finds authorities !!!

[1] Manually link (staff client) auth "Lubbock" to bib "Arctic Whalers" -- 
now linked, 35 other Lubbock bibs not linked.  Is this a question of zebra 
re-indexing?

So:  KOHA_CONF=/etc/koha/koha-conf.xml PERL5LIB=/usr/share/koha/lib 
./bin/migration_tools/rebuild_zebra.pl -a -r -v
and  KOHA_CONF=/etc/koha/koha-conf.xml PERL5LIB=/usr/share/koha/lib 
./bin/migration_tools/rebuild_zebra.pl -b -r -v -x

koha at nelson:/usr/share/koha$ ./bin/link_bibs_to_authorities.pl
... processed 100 records
/ ... /
... processed 14900 records

Bib authority heading linking report
------------------------------------
Number of bibs checked:       14911
Number of bibs modified:      1
Number of bibs with errors:   0
koha at nelson:/usr/share/koha$

All this did was to *un-link" the bib/auth link that I had manually entered 
at [1] above. Could someone involved with signing off bug 5683 please 
explain why link==unlink?

Help - please.

Paul