Serve from cache but fire request to upstream server to increment page view counter

[Antonio P.P. Almeida]

> Thanks Appa.
>
> Why would you say this is not reliable? Is there data or experience to
> suggest? The semantic is awesome. Precisely what I've been looking for.
>
> -Cherian

Well from remarks that core devs of Nginx have posted here before,
referring to it as "hack" (SIC). In fact it's not even documented in the
official docs.

I'm not sure if that's an overlook or has deeper meanings related to the
quality of the said directive concept/code.

--appa