[Help-bash] Where is the exit coming from when invoking bash -i from command line?

[Peng Yu]

Hi, I see `exit` is shown below. But I don't understand where it is
coming from. Does anybody know?

~$ cat main.sh
#!/usr/bin/env bash
# vim: set noexpandtab tabstop=2:

bash --init-file <(echo "export PS1='\u '") -i <<'EOF'

EOF
~$ ./main.sh
testuser
testuser exit
$ echo $USER
testuser

-- 
Regards,
Peng