uvloop closes underlying sockets that were established outside upon end of asyncio.run()

This seem to be version/OS unrelated. Sample:

import asyncio
import socket
import uvloop

b = bytes('{"msg": "test"}', 'utf-8')


async def main_async(sock: socket.socket):
    _, writer = await asyncio.open_unix_connection(sock=sock)
    writer.write(b)
    await writer.drain()


if __name__ == '__main__':
    sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
    sock.connect('data/sockets/echo_server.sock')
    sock.sendall(b)
    uvloop.install()
    asyncio.run(main_async(sock))  # sock gets wrongly closed on asyncio.run() termination
    sock.sendall(b)  # Exception here OSError: [Errno 9] Bad file descriptor

Last line result in exception "OSError: [Errno 9] Bad file descriptor" because sock gets closed right after asyncio.run() terminates. It is wrong behavior, because sock was created outside of asyncio loop and has to be left untouched. The issue doesn't occur using regular asyncio loop.

Start by running the provided Unix-socket reproducer and compare uvloop with the regular asyncio loop. Trace the socket ownership and close lifecycle around asyncio.open_unix_connection() and asyncio.run(); done means the externally created socket remains usable after asyncio.run() and the regression is covered by a test.