Starting with Vim 8.0.1308Vim 8.0.1308 (Nov 2017), you can use the --not-a-term
"--not-a-term" option to suppress this message; for example with quit
with "quit":
$ echo hello | vi - --not-a-term -esc '%p|q!'
hello
Or with exit
"exit":
$ echo hello | vi - --not-a-term -esc 'x!/dev/stdout'
hello