What happened to the alias this = identifier syntax in 2.062?

[Martin]

On Friday, 22 February 2013 at 14:55:19 UTC, bearophile wrote:
> Martin:
>
>> Was something changed intentionally or is this a bug?
>
> It was changed intentionally, but only for alias this. That 
> syntax is allowed still for other aliases.
>
> Bye,
> bearophile

I see, thanks. What was the reason for not allowing alias this = 
identifier?