ValueError: cannot override codec when using set_builtin_type_codec with connection pool

[dgelvin]

• asyncpg version: 0.8.4
• PostgreSQL version: 9.6.0
• Python version: 3.5.1
• Platform: Linux
• Do you use pgbouncer?: No
• Do you use the wheel package or built locally
  (if locally, which version of Cython was used)?: Wheel package
• Can you the issue be reproduced when running under
  uvloop?:

I have the following coroutine for setting up hstore support:

async def setup_connection(connection):
    await connection.execute('CREATE EXTENSION IF NOT EXISTS hstore')
    await connection.set_builtin_type_codec('hstore', codec_name='pg_contrib.hstore')

I am creating a connection pool with:

pool = await asyncpg.create_pool(setup=setup_connection, loop=loop)

Everything works at first, but after an indeterminate number of async with pool.acquire() as connection: calls I eventually get the following exception:
ValueError: cannot override codec for type 1419710

Is there another way I should be enabling hstore support with a connection pool?

Thanks for the great library.

[1st1]

Fixed in v0.9.0. Use new init parameter to create_pool.