copy_from_query output function receives bytearray

[johanfforsberg]

• asyncpg version: 0.25.0
• PostgreSQL version: 13.4 (Ubuntu 13.4-1.pgdg21.04+1) + Timescale 2.4.2
• Do you use a PostgreSQL SaaS? If so, which? Can you reproduce the issue with a local PostgreSQL install?:
• Python version: 3.9.7
• Platform: Ubuntu 21.10
• Do you use pgbouncer?: No
• Did you install asyncpg with pip?: Yes
• If you built asyncpg locally, which version of Cython did you use?:
• Can the issue be reproduced under both asyncio and uvloop?: Could not try without uvloop because of https://github.com/MagicStack/asyncpg/issues/240

Hi! The documentation states that a coroutine function passed as output argument will receive a bytes argument, but when I do this I get bytearray. Seems like a bug either with documentation or the code.