Comment 3 for bug 1163372

Indeed, the problem is that https://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_unix-timestamp :

"""
The server interprets date as a value in the current time zone and converts it to an internal value in UTC.
"""

So the tools need to SET time_zone='+0:00'; so that UNIX_TIMESTAMP() returns the ts from the server as UTC (and it was inserted as UTC using UTC_TIMESTAMP()).