BUG #10911: pg_upgrade appears to lose the transaction id epoch

The following bug has been logged on the website:

Bug reference: 10911
Logged by: Greg Burek
Email address: gregburek(at)heroku(dot)com
PostgreSQL version: 9.0.17
Operating system: Ubuntu Linux
Description:

When upgrading a 9.0.17 db to 9.3.4 via pg_upgrade, the transaction ids
appear to fall backward in time:

>From before the upgrade:
=> SELECT txid_snapshot_xmax(txid_current_snapshot());
txid_snapshot_xmax
--------------------
66329538555
(1 row)

After the upgrade:

=> SELECT txid_snapshot_xmax(txid_current_snapshot());
txid_snapshot_xmax
--------------------
1905029395
(1 row)

Looking at pg_control before the upgrade:
$ pg_controldata /database/ | grep -i nextxid
Latest checkpoint's NextXID: 15/1905728256

After the upgrade:
$ pg_controldata /database/ | grep -i nextxid
Latest checkpoint's NextXID: 0/1905029398

This is an unexpected loss of the higher order bits when the upgrade is
performed. Is it possible to preserve the epoch across the upgrade?

thanks,
Greg