If a result is chosen from the auto-complete menu, the text in the input field is replaced, but what is submitted is what was originally entered. If one presses 'down' or some other key to re-engage the auto-complete on the new clicked-on text, then that will be submitted.
It does something now. See commit 4ede4e65. It only works for mouse clicks though, which is rather annoying. Look into figuring out how to get 'tab' and 'enter' to work as expected.
If a result is chosen from the auto-complete menu, the text in the input field is replaced, but what is submitted is what was originally entered. If one presses 'down' or some other key to re-engage the auto-complete on the new clicked-on text, then that will be submitted.