use asyncio.create_subprocess_shell run sbatch not work well

Question

A content like this

Class Tcontent:
    def __init__(self, op_file):
        self.op_file = op_file
    
    async def __aenter__(self):
        sbatch_cmd = f"sbatch -p test -q test -c 1 --mem 1000 -o {self.op_file} myscript.sh"
        proc = await asyncio.create_subprocess_shell(sbatch_cmd, stderr=asyncio.subprocess.PIPE, stdout=asyncio.subprocess.PIPE)
        stdout, stderr = await proc.communicate()
        if proc.returncode != 0:
            raise Exception
        else:
            with open(op_file) as tf:
                out = tf.read()
            return out
    async def __aexit__(self, exc_type, exc_val, exc_tb):
        ***

Then I call it

async with Tcontent('sbatch.out') as x:
    print(x)

It will raise No such file or directory sbatch.out

when I set breakpoint before with open(op_file) as tf, then continue run, it works well