Proxy authentication fails if http proxy disconnects after issuing 407

To reproduce:

• set up a proxy, for example fiddler: (http://www.fiddler2.com/fiddler2/))
• enable authentication (Rules/Require Proxy Authentication)
• launch $(QTDIR)\demos\release\browser.exe
• set proxy Edit/Preferences/Enable proxy (localhost:8888)
• go to an HTTP site (for example http://xkcd.com)
• observe how proxy authentication dialog comes up
• go to HTTPS site (for example https://gmail.com)

Expected: proxy password dialog shows up (or page loads if correct password was given before)
Actual: page is never loaded, password is never asked. Proxy registers one CONNECT request.

On a more technical note:
Both QHttp and QNetworkAccessManager can't handle authenticated proxy when using SSL. proxyAuthenticationRequired signal is emitted, but finished signal on QNetworkReply (or httpRequestFinished on QHttp) is emitted as well. Looks like a bug in secure socket.