After update to 0.5.7: SQLSTATE[HY000]: General error: 1525 Incorrect TIMESTAMP value: '-1'

Created by: jsuelwald

Hi,

i've updated an existing installation of PartDB to 0.5.7 and on /system_log.php this error occured:

Datenbankfehler: SQLSTATE[HY000]: General error: 1525 Incorrect TIMESTAMP value: '-1'

SQL-Query: SELECT COUNT(id) AS count from log WHERE level <= ? AND (datetime >= ?) ORDER BY log.datetime DESC

Parameter: Array ( [0] => 7 [1] => -1 )