(And how can I get all of my lookup fields to have type ahead?)
So here is the weird thing: I have several lists and lookups which I am deploying as a part of a .wsp.
Of all of the lookups that are deployed, one gets this nice little type-ahead feature in the UI which I thought I had to add a third party JavaScript library to accomplish.
See evidence below:

To be clear, this is not a managed metadata field; it's a regular lookup field. But the markup is definitely different in the HTML. It renders as a input type=textbox and img which overlays a select

To wit, I have not been able to get any of my other lookup fields to behave this way. Only this one.
So my question is what is the magic sauce that allows me to get this behavior "for free"?