configuring timezone

Timezone configuration parameter (defaulting to system timezone) worked fine 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 entries timezone<http://www.postgresql.org/docs/9.2/static/runtime-config-client.html#GUC-TIMEZONE> and log_timezone<http://www.postgresql.org/docs/9.2/static/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 will probe system's timezone on startup (default to OS timezone on startup) instead 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 during 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