mysql versions prior to 5.0.74 have trouble export/import with leap seconds

From the MySQL manual:

http://dev.mysql.com/doc/refman/5.0/en/time-zone-leap-seconds.html

9.7.2. Time Zone Leap Second Support

Before MySQL 5.0.74, if the operating system is configured to return leap seconds from OS time calls or if the MySQL server uses a time zone definition that has leap seconds, functions such as NOW() could return a value having a time part that ends with :59:60 or :59:61. If such values are inserted into a table, they would be dumped as is by mysqldump but considered invalid when reloaded, leading to backup/restore problems.

As of MySQL 5.0.74, leap second values are returned with a time part that ends with :59:59. This means that a function such as NOW() can return the same value for two or three consecutive seconds during the leap second. It remains true that literal temporal values having a time part that ends with :59:60 or :59:61 are considered invalid.