Another issue. I write OpenID authentication system (Valve Steam community). I found some stack corruption or something similar while downloading some gzipped pages.
In particular, auth checking page of the Steam OpenID system. Test case:

shared static this() {
    runTask({
        logInfo("start task");
        requestHTTP("https://steamcommunity.com/openid/login?openid.mode=check_authentication", (scope req) {
            //req.headers.remove("Accept-Encoding");
        }, (scope res) {
            logInfo("downloading");
            string data = res.bodyReader.readAllUTF8();
            logInfo("length = %s", data.length);
        });
        logInfo("end task");
    });
}

Looks like responder callback never returns. Log misses "end task":

d:\tmp\test>test
start task
downloading
length = 51

If turn off compression by removing Accept-Encoding header, then downloading works fine.