Call `emacs -q` do `M-x ansi-term RET` try to kill buffer - a prompt
with `yes` or `no` will be provided. Cancel and call `M-: (fset
'yes-or-no-p 'y-or-n-p) RET`, and try to kill ansi-term buffer
again. Prompt will still ask to input `yes` or `no` instead of `y` or
`n`. Works in master branch of Emacs run with `-q`.

-- 
Best regards,
Andrey Orst