post-proxy and detecting dead upstream realms

[Phil Mayers]

I'd like to do something like this:

pre-proxy {
   update control {
     Tmp-Integer-0 := "%{some_scoring_thing:%{Realm}}"
   }
   if (Tmp-Integer-0 > 10) {
     reject
   }
}

post-proxy {
   Post-Proxy-Type Timeout {
     some_scoring_thing
   }
}

The idea is that I have an upstream proxy (eduroam) with potentially 
hundreds of realms behind it. Some realms just don't respond, and when 
that happens above a certain threshold, I'd like to locally blacklist 
the realm and avoid sending them to the upstream proxy for some time period.

I'm not willing to maintain a manual blacklist.

The question: what method can I use to run a module/expansion when a 
proxy request isn't replied to. "Post-Proxy-Type Fail" doesn't seem to 
do it (in fact, I can't make it trigger at all in my tests).

Looking at the source this might be impossible?