MARC::Record utf8 strange & weird problem...

Still hacking for Koha 3.0

I face a very strange problem. Here is the description :
- I add a biblio with some unicode => works fine.
- I modify the biblio => still works fine.
- I add an item => OK
- I modify the biblio again => reading the biblio on database is OK, but 
when saving it, all accented chars are reencoded.

In Koha, the biblio and the items are stored in a MARC::Record (in XML 
in the database).

When you update a biblio, Koha does :
- get the biblio you just edit

#retrieve the  revious complete record
my $oldRecord = GetMarcBiblio( $biblionumber );
# retrieve items
my @fields = $oldRecord->field( $itemtag );
# append them to new record
$record->append_fields( @fields );

- save the biblio.

I have Dumper()-ed the records before and after the append_fields = they 
are the same.
I have as_formatted-ed the record before and after the append_fields = 
they differ.

Seems Perl has forgotten that the $record is utf8 and he reencodes the 
record.

Any idea to solve the problem ?

Here is the Dumper and the as_formatted I get before and after inserting 
the field :
BEFORE : $VAR1 = bless( {
     '_leader' => '00230     2200097   4500',
     '_warnings' => [],
     '_fields' => [
         bless( {
                 '_is_control_field' => 1,
                 '_data' => '',
                 '_warnings' => [],
                 '_tag' => '009'
             }, 'MARC::Field' ),
         bless( {
                 '_is_control_field' => '',
                 '_ind2' => ' ',
                 '_subfields' => [
                     'a',
                     '20070809              frey50       '
                     ],
                 '_warnings' => [],
                 '_tag' => 100,
                 '_ind1' => ' '
             }, 'MARC::Field' ),
         bless( {
                 '_is_control_field' => '',
                 '_ind2' => ' ',
                 '_subfields' => [
                     'a',
                     'title \xc3\xa9 / \xc3\xa0'<<<<<<<< interesting line
                     ],
                 '_warnings' => [],
                 '_tag' => 200,
                 '_ind1' => ' '
             }, 'MARC::Field' )
         ]
}, 'MARC::Record' );

as formatted :
==================
LDR 00230     2200097   4500
009
100    _a20070809              frey50
200    _atitle \xc3\xa9 / \xc3\xa0 <<<<<<<< interesting line

INSERT :
======================
  $VAR1 = bless( {
         '_is_control_field' => '',
         '_ind2' => ' ',
         '_subfields' => [
                 'b',
                 'SED',
                 'c',
                 'SED',
                 'e',
                 'Magasin',
                 'k',
                 'item callnumber',
                 'o',
                 '0',
                 'f',
                 '12346598',
                 '9',
                 '58433'
                 ],
         '_warnings' => [],
         '_tag' => 995,
         '_ind1' => ' '
     }, 'MARC::Field' );

AFTER :
=================
  $VAR1 = bless( {
         '_leader' => '00230     2200097   4500',
         '_warnings' => [],
         '_fields' => [
         bless( {
                 '_is_control_field' => 1,
                 '_data' => '',
                 '_warnings' => [],
                 '_tag' => '009'
             }, 'MARC::Field' ),
         bless( {
                 '_is_control_field' => '',
                 '_ind2' => ' ',
                 '_subfields' => [
                     'a',
                     '20070809              frey50       '
                     ],
                 '_warnings' => [],
                 '_tag' => 100,
                 '_ind1' => ' '
                 }, 'MARC::Field' ),
         bless( {
             '_is_control_field' => '',
             '_ind2' => ' ',
             '_subfields' => [
                 'a',
                 'title \xc3\xa9 / \xc3\xa0'<<<<<<<< interesting line
                 ],
             '_warnings' => [],
             '_tag' => 200,
             '_ind1' => ' '
             }, 'MARC::Field' ),
         bless( {
                 '_is_control_field' => '',
                 '_ind2' => ' ',
                 '_subfields' => [
                         'b',
                         'SED',
                         'c',
                         'SED',
                         'e',
                         'Magasin',
                         'k',
                         'item callnumber',
                         'o',
                         '0',
                         'f',
                         '12346598',
                         '9',
                         '58433'
                         ],
                 '_warnings' => [],
                 '_tag' => 995,
                 '_ind1' => ' '
             }, 'MARC::Field' )
         ]
     }, 'MARC::Record' );
as formatted : LDR 00230     2200097   4500
009
100    _a20070809              frey50
200    _atitle \xc3\x83\xc2\xa9 / \xc3\x83\xc2\xa0 <<<< interesting line
995    _bSED
        _cSED
        _eMagasin
        _kitem callnumber
        _o0
        _f12346598
        _958433 at /home/paul/koha.dev/head/C4/Biblio.pm line 387.
-- 
Paul POULAIN et Henri Damien LAURENT
Consultants indépendants en logiciels libres et bibliothéconomie 
(http://www.koha-fr.org)
Tel : 04 91 31 45 19