Bug 30996

This is a weird issue. It could very well be something particular to my setup, but I am at a loss as to what it might be, so here goes...

This is happening on a regular Koha 20.11.13.000, installed with the Debian packages, on Ubuntu 20.04.3. 

I have a script that downloads records from the Swedish national library Libris, does some checking and some massaging, and then imports the records into Koha with either AddBiblio or ModBiblio. The script can be found here: https://github.com/Libriotech/ftp2koha

About a month ago messages like these started to show up in the logs for some of the imported records: 

Wide character in warn at /usr/share/perl5/MARC/Charset.pm line 384.
no mapping found at position 1 in ビードマルク, マッティン, at /usr/share/perl5/MARC/Charset.pm line 384.

Records that produce this error show broken chars, with chars like äöå shown as a diamond with a question mark in it. 

The records look ok before they are imported, and tools like yax-marcdump does not show errors for them. Position 9 in the leader is "a", to indicate the records are UTF8. Three records in one file are attached. 

I have tried to reduce the problem down to a minimal case, and come up with this script: 

--------------------------------------------------------------------

#!/usr/bin/perl

use Modern::Perl;
use C4::Biblio qw( ModBiblio );
use MARC::File::XML ( BinaryEncoding => 'utf8', RecordFormat => 'MARC21' );

my $records = MARC::File::XML->in( 'export_2022_06_16_1120_orig.marcxml' );

# Start transaction
my $schema = Koha::Database->new()->schema();
$schema->storage->txn_begin();

my %map = (
    'p4rdqd4nm9f4dhv3' => 349078,
    'jzzcjbt4gt0f0z8w' => 348789,
    '1fmgws1lzrk71k2t' => 349079,
);

RECORD: while ( my $record = $records->next() ) {

    say $record->leader;
    say "=========^==============";

    $record->encoding( 'UTF-8' );

    my $id = $record->field( '001' )->data;
    my $biblionumber = $map{ $id };

    if ( $ARGV[0] > 1 ) {
        say ModBiblio( $record, $biblionumber, '' );
    }

}

# End transaction
$schema->storage->txn_rollback();

--------------------------------------------------------------------

The results of running that script are different depending on if ModBiblio gets called or not. With "0" as the argument it does not get called and everything looks ok. Leader pos 9 is "a":

$ sudo koha-shell -c "perl -MCarp::Always test_minimal.pl 0" norrbott
     cim a       7i 4500
=========^==============
     ngm a       7i 4500
=========^==============
     cim a       7i 4500
=========^==============

With "2" as argument, ModBiblio does get called, and there are errors related to encoding (from the call to $records->next()), from the second and third record. Notice also that leader pos 9 for record number two and three is now empty! So when ModBiblio is triggered, the UTF8 indicator is suddenly gone, and as far as I can see, this is what is causing the encoding errors:

$ sudo koha-shell -c "perl -MCarp::Always test_minimal.pl 2" instancename
     cim a       7i 4500
=========^==============
1
Wide character in warn at /usr/share/perl5/Carp/Always.pm line 18.
no mapping found at position 1 in ビードマルク, マッティン, at /usr/share/perl5/MARC/Charset.pm line 384.
	MARC::Charset::utf8_to_marc8("\x{30d2}\x{3099}\x{30fc}\x{30c8}\x{3099}\x{30de}\x{30eb}\x{30af}, \x{30de}\x{30c3}\x{30c6}\x{30a3}\x{30f3},") called at /usr/share/perl5/MARC/File/XML.pm line 480
	MARC::File::XML::decode(MARC::File::XML=HASH(0x56070fb9c278), "<record><leader>     ngm a       7i 4500</leader><controlfiel"...) called at /usr/share/perl5/MARC/File.pm line 110
	MARC::File::next(MARC::File::XML=HASH(0x56070fb9c278)) called at test_minimal.pl line 19
     ngm         7i 4500
=========^==============
Use of uninitialized value in join or string at /usr/share/perl5/MARC/Field.pm line 696.
	MARC::Field::as_usmarc(MARC::Field=HASH(0x560718749560)) called at /usr/share/perl5/MARC/File/USMARC.pm line 274
	MARC::File::USMARC::_build_tag_directory(MARC::Record=HASH(0x5607186ea458)) called at /usr/share/perl5/MARC/File/USMARC.pm line 313
	MARC::File::USMARC::encode(MARC::Record=HASH(0x5607186ea458)) called at /usr/share/perl5/MARC/Record.pm line 474
	MARC::Record::as_usmarc(MARC::Record=HASH(0x5607186ea458)) called at /usr/share/koha/lib/C4/Biblio.pm line 3054
	C4::Biblio::ModBiblioMarc(MARC::Record=HASH(0x560718457c30), 348789, "") called at /usr/share/koha/lib/C4/Biblio.pm line 381
	C4::Biblio::ModBiblio(MARC::Record=HASH(0x560718457c30), 348789, "") called at test_minimal.pl line 30
1
     cim         7i 4500
=========^==============
1

Things I have checked: 

- /usr/share/koha/lib/C4/Biblio.pm has not been updated since well before the problems started
- I can not see any plugins that do suspicious things

Anyone got a hunch what might be causing this, or where to start looking for a solution?