That's incorrect -- it's still possible. Alpha is the freeze for "big" features. Little features can still be added up till the release of the beta. A minor enhancement to an existing field would definitely fall under the category of a minor feature.
However, this all hinges on someone getting:
1) consensus on a design,
2) a commit-ready patch that implements that design.
Reading the ticket, we haven't yet achieved (1). The most recent comment was 9 months ago, and hasn't been followed up. For the record, that comment doesn't "promise" anything -- it's just saying that if a change is going to happen, it couldn't happen any sooner than 1.5 (since 1.4 was already out, and a change like this *won't* be back ported).
So - if you want this, now would be a very good time to do exactly what the ticket says, and lead the discussion advocating it.
Yours,
Russ Magee %-)