There is some related discussion here
http://postgresql.1045698.n5.nabble.com/to-timestamp-returns-the-incorrect-result-for-the-DST-fall-over-time-td3327393.html
But it amounts to the same thing: TO_TIMESTAMP() is not apt for dealing with
plain TIMESTAMP
(without time zones).
Hence, there is no fiable way of parsing a "local date time", using this
function, I must resort to
workarounds as defining a new function that internally sets, for
example, set LOCAL timezone = 'UTC'
Hernán J. González