At HEAD, you can use the new "Browse" dialog to browse through a long list of similarly-named items -- you can try it on this install by clicking the new icon inside the tokenizer control:

See also T6974 (discussion of preventing duplicates in the Action selectors) and T7858 (discussion of making it easier to get to this dialog from the bottom of a long result list).

I'd hesitate to implement the solution exactly as described because I worry it would be confusing to type an item which you know has matches and get nothing back. This isn't insurmountable, but I think it's significantly more clear to always show the match (ideally, perhaps we would visually indicate that it has already been selected in the dropdown, though).