BUG #6532: pg_upgrade fails on Python stored procedures

The following bug has been logged on the website:

Bug reference:      6532
Logged by:          Stuart Bishop
Email address:      stuart@stuartbishop.net
PostgreSQL version: 9.1.3
Operating system:   Ubuntu
Description:=20=20=20=20=20=20=20=20

The 9.1.3 changelog states pg_upgrade's handing of plpython stored
procedures was fixed, but that does not appear to be the case:

postgres@aargh:~$ /usr/lib/postgresql/9.1/bin/pg_upgrade --version
pg_upgrade (PostgreSQL) 9.1.3
postgres@aargh:~$ /usr/lib/postgresql/9.1/bin/pg_upgrade=20
--old-bindir=3D/usr/lib/postgresql/8.4/bin
--new-bindir=3D/usr/lib/postgresql/9.1/bin --old-datadir=3D8.4/main
--new-datadir=3D9.1/mig --old-port=3D5433 --new-port=3D5435
Performing Consistency Checks
-----------------------------
Checking current, bin, and data directories                 ok
Checking cluster versions                                   ok
Checking database user is a superuser                       ok
Checking for prepared transactions                          ok
Checking for reg* system oid user data types                ok
Checking for contrib/isn with bigint-passing mismatch       ok
Checking for large objects                                  ok
Creating catalog dump                                       ok
Checking for prepared transactions                          ok
Checking for presence of required libraries                 ok

| If pg_upgrade fails after this point, you must
| re-initdb the new cluster before continuing.
| You will also need to remove the ".old" suffix
| from 8.4/main/global/pg_control.old.

Performing Upgrade
------------------
Adding ".old" suffix to old global/pg_control               ok
Analyzing all rows in the new cluster                       ok
Freezing all rows on the new cluster                        ok
Deleting new commit clogs                                   ok
Copying old commit clogs to new server                      ok
Setting next transaction id for new cluster                 ok
Resetting WAL archives                                      ok
Setting frozenxid counters in new cluster                   ok
Creating databases in the new cluster                       ok
Adding support functions to new cluster                     ok
Restoring database schema to new cluster=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20
psql:/var/lib/postgresql/pg_upgrade_dump_db.sql:3992: ERROR:  could not
access file "$libdir/plpython": No such file or directory

There were problems executing "/usr/lib/postgresql/9.1/bin/psql" --set
ON_ERROR_STOP=3Don --no-psqlrc --port 5435 --username "postgres" -f
"/var/lib/postgresql/pg_upgrade_dump_db.sql" --dbname template1 >>
"/dev/null"
Failure, exiting


The relevant section of pg_upgrade_dump_db.sql is:

CREATE FUNCTION plpython_call_handler() RETURNS language_handler
    LANGUAGE c
    AS '$libdir/plpython', 'plpython_call_handler';