BUG #12617: DETAIL: Could not read from file "pg_subtrans/06F8" at offset 90112: Success.

The following bug has been logged on the website:

Bug reference:      12617
Logged by:          Davi Koscianski Vidal
Email address:      davividal@gmail.com
PostgreSQL version: 9.4.0
Operating system:   Linux CentOS 6.6 x86_64
Description:

My scenario: I have a daily physical backup from my production server
(9.1).
I create a 9.1 cluster from it and upgrade it to 9.4 daily. After that, I
deploy a bunch of changes using sqitch (sqitch.org). Again: I do it on a
daily basis, but this is the first time I faced this issue:

$ sqitch deploy -t sandbox views/sistema.sf_guard_user@HEAD
Deploying changes through views/sistema.sf_guard_user to sandbox
  + data_migration/rate_plan.payment_policies ...............
psql:sql/deploy/data_migration/rate_plan.payment_policies.sql:21: ERROR:
could not access status of transaction 116940611
DETAIL:  Could not read from file "pg_subtrans/06F8" at offset 90112:
Success.
CONTEXT:  while updating tuple (6302,20) in relation "rate_daily_policies"
not ok

Re-running the command yields the exactly same error.
Running from psql give the same output:

reserva_imediata=# ALTER TABLE rate_plan.rate_daily_policies DISABLE TRIGGER
USER;
ALTER TABLE
reserva_imediata=# ALTER TABLE rate_plan.payment_policies DISABLE TRIGGER
USER;
ALTER TABLE
reserva_imediata=# UPDATE rate_plan.rate_daily_policies AS rp
reserva_imediata-#         SET
reserva_imediata-#         (
reserva_imediata(#                   discount,
reserva_imediata(#                   min_stay,
reserva_imediata(#                   max_stay,
reserva_imediata(#                   meal_plan_type_ota_code
reserva_imediata(#           ) = (
reserva_imediata(#                   pp.discount,
reserva_imediata(#                   pp.min_stay,
reserva_imediata(#                   pp.max_stay,
reserva_imediata(#                   pp.meal_plan_type_ota_code
reserva_imediata(#           )
reserva_imediata-# FROM rate_plan.payment_policies AS pp
reserva_imediata-# WHERE pp.policy_id = rp.policy_id_payment;
ERROR:  could not access status of transaction 116940611
DETAIL:  Could not read from file "pg_subtrans/06F8" at offset 90112:
Success.
CONTEXT:  while updating tuple (6302,20) in relation "rate_daily_policies"
reserva_imediata=# ALTER TABLE rate_plan.rate_daily_policies ENABLE TRIGGER
USER;
ALTER TABLE
reserva_imediata=# ALTER TABLE rate_plan.payment_policies ENABLE TRIGGER
USER;
ALTER TABLE

The command I used to upgrade was: /usr/pgsql-9.4/bin/pg_upgrade -d
/var/lib/pgsql/9.1/data -D /var/lib/9.4/data -b /usr/pgsql/9.1/bin -B
/usr/pgsql/9.4/bin

What other info can I provide?
My database is 30 GB in size and have customers data, so it is *very* hard
(or even impossible) to provide a dump.