Pgbouncer and 'prepared statement does not exist'

[AmatanHead]

• asyncpg version: 0.12.0
• PostgreSQL version: 9.6
• Python version: 3.6.2
• Platform: ubuntu 16.04
• Do you use pgbouncer?: yes
• Did you install asyncpg with pip?: yes
• Can the issue be reproduced under both asyncio and
  uvloop?: don't know

Hello! I'm trying to use asyncpg with pgbouncer. I've set statement_cache_size=0 but I still get errors. What am I doing wrong?

In [1]: import os, asyncpg, asyncio

In [2]: loop = asyncio.get_event_loop()

In [3]: conn = loop.run_until_complete(asyncpg.connect(
   ...:     host = 'pgaas.mail.yandex.net',
   ...:     port = 12000,
   ...:     user = 'statinfra_api',
   ...:     database = 'statinfra_api_beta',
   ...:     password=os.environ['DB_PASSWORD'],
   ...:     ssl=True,
   ...:     statement_cache_size=0
   ...: ))

In [4]: loop.run_until_complete(conn.fetch('SELECT * FROM tasks'))
---------------------------------------------------------------------------
InvalidSQLStatementNameError              Traceback (most recent call last)
<ipython-input-5-8a44237acb87> in <module>()
----> 1 loop.run_until_complete(conn.fetch('SELECT * FROM tasks'))

/usr/lib/python3.6/asyncio/base_events.py in run_until_complete(self, future)
    465             raise RuntimeError('Event loop stopped before Future completed.')
    466 
--> 467         return future.result()
    468 
    469     def stop(self):

~/.virtualenvs/statbox-abt-backend/lib/python3.6/site-packages/asyncpg/connection.py in fetch(self, query, timeout, *args)
    339         """
    340         self._check_open()
--> 341         return await self._execute(query, args, 0, timeout)
    342 
    343     async def fetchval(self, query, *args, column=0, timeout=None):

~/.virtualenvs/statbox-abt-backend/lib/python3.6/site-packages/asyncpg/connection.py in _execute(self, query, args, limit, timeout, return_status)
   1186         timeout = self._protocol._get_timeout(timeout)
   1187         with self._stmt_exclusive_section:
-> 1188             return await self._do_execute(query, executor, timeout)
   1189 
   1190     async def _executemany(self, query, args, timeout):

~/.virtualenvs/statbox-abt-backend/lib/python3.6/site-packages/asyncpg/connection.py in _do_execute(self, query, executor, timeout, retry)
   1197     async def _do_execute(self, query, executor, timeout, retry=True):
   1198         if timeout is None:
-> 1199             stmt = await self._get_statement(query, None)
   1200         else:
   1201             before = time.monotonic()

~/.virtualenvs/statbox-abt-backend/lib/python3.6/site-packages/asyncpg/connection.py in _get_statement(self, query, timeout, named)
    290                 self._types_stmt = await self.prepare(self._intro_query)
    291 
--> 292             types = await self._types_stmt.fetch(list(ready))
    293             self._protocol.get_settings().register_data_types(types)
    294 

~/.virtualenvs/statbox-abt-backend/lib/python3.6/site-packages/asyncpg/prepared_stmt.py in fetch(self, timeout, *args)
    155         :return: A list of :class:`Record` instances.
    156         """
--> 157         data = await self.__bind_execute(args, 0, timeout)
    158         return data
    159 

~/.virtualenvs/statbox-abt-backend/lib/python3.6/site-packages/asyncpg/prepared_stmt.py in __bind_execute(self, args, limit, timeout)
    194         protocol = self._connection._protocol
    195         data, status, _ = await protocol.bind_execute(
--> 196             self._state, args, '', limit, True, timeout)
    197         self._last_status = status
    198         return data

~/.virtualenvs/statbox-abt-backend/lib/python3.6/site-packages/asyncpg/protocol/protocol.pyx in bind_execute (asyncpg/protocol/protocol.c:66799)()

InvalidSQLStatementNameError: prepared statement "__asyncpg_stmt_1__" does not exist