Could you please run this in a console (replacing "w3aftest" with the correct hostname in your case) and paste the output ?

python
import socket
socket.getaddrinfo('w3aftest',1)
socket.gethostbyname('w3aftest')

That worked - it was able to resolve the address.

Also, if possible, could you please do a "svn update" of the project and run the scan again ?

Done - updated to revision 159. I then reran the scan with console verbosity set to 10. Here is the output.

We failed to reach the server. Reason: "(113, 'No route to host')"; going to retry.
Traceback for this error: Traceback (most recent call last):
File "/home/kroyster/w3af/core/data/url/xUrllib.py", line 300, in _send
    res = self._opener.open( req )
File "urllib2.py", line 374, in open
    response = self._open(req, data)
File "urllib2.py", line 392, in _open
    '_open', req)
File "urllib2.py", line 353, in _call_chain
    result = func(*args)
File "/home/kroyster/w3af/core/data/url/handlers/keepalive.py", line 380, in https_open
    return self.do_open(req)
File "/home/kroyster/w3af/core/data/url/handlers/keepalive.py", line 263, in do_open
    raise urllib2.URLError(err)
URLError: <urlopen error (113, 'No route to host')>

The above output repeats 2 more times then....

The target URL: https://preprod.olcsc.ntta.org/olcsc/ is unreachable.
Error description: Too many retries when trying to get: https://preprod.olcsc.ntta.org/olcsc/
Called _discoverWorker()
Called _bruteforce()
No URLs found by discovery.

Is w3af trying to ping or traceroute the target before scanning? That will always fail for this scenario, because I'm being blocked by their firewall. That's why I need to go through the proxy.