Bug 24002: Incorrect DATE value: '' in C4/Bookseller.pm

Bug 24002: Incorrect DATE value: '' in C4/Bookseller.pm

t/db_dependent/Bookseller.t .. 3/86 DBD::mysql::st execute failed: Incorrect DATE value: '' [for Statement "
        SELECT DISTINCT aqbasket.booksellerid, aqbooksellers.name
        FROM aqorders LEFT JOIN aqbasket ON aqorders.basketno=aqbasket.basketno
        LEFT JOIN aqbooksellers ON aqbasket.booksellerid = aqbooksellers.id
        WHERE
            ( datereceived = ''
            OR datereceived IS NULL
            OR aqorders.quantityreceived < aqorders.quantity
            )
            AND aqorders.quantity - COALESCE(aqorders.quantityreceived,0) <> 0
            AND aqbasket.closedate IS NOT NULL
    "] at /kohadevbox/koha/C4/Bookseller.pm line 100.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>