configuring timezone

Timezone configuration parameter (defaulting to system timezone)  worked fi=
ne for us before upgrading from 8.4. to 9.2.

Now we've got a problem.
9.2 Release Notes says:

*  Identify the server time zone during initdb, and set postgresql.conf ent=
ries timezone<http://www.postgresql.org/docs/9.2/static/runtime-config-clie=
nt.html#GUC-TIMEZONE> and log_timezone<http://www.postgresql.org/docs/9.2/s=
tatic/runtime-config-logging.html#GUC-LOG-TIMEZONE> accordingly (Tom Lane)

This avoids expensive time zone probes during server start.

Question: is there any way to revert back to old behavior so that server wi=
ll probe system's timezone on startup (default to OS timezone on startup) i=
nstead setting it during initdb?
Obviously, without recompiling/rebuilding Postgres.

I'm dealing with the situation, where system is being built in one timezone=
 (could be anywhere around the globe), and then moved to other (not known d=
uring system build) location with different timezone.
After relocation, OS timezone will change, but we can't allow user to edit =
timezone parameter in  Postgresql.conf.

Regards,
Igor Neyman