KTcpSocket ::errorString () == "Unknown error" after KTcpSocket ::waitForBytesWritten sets KTcpSocket ::error.

Reproducible: Always

Steps to Reproduce:
  0. Modify KTcpSocketTest::statesIana in the following way:
oid KTcpSocketTest::statesIana()
{
    //A connection to a real internet host
    KTcpSocket s (this);
    connect(& s, SIGNAL(hostFound()), this, SLOT(states_hostFound()));
    QCOMPARE(s .state(), KTcpSocket::UnconnectedState);
    s .connectToHost("www.iana.org", 80);
    QCOMPARE(s .state(), KTcpSocket::HostLookupState);
    s .write(HTTPREQUEST);
    QCOMPARE(s .state(), KTcpSocket::HostLookupState);
    s .waitForBytesWritten(2500); if (KTcpSocket ::UnknownError == s .error ()) {
    QCOMPARE(s .state(), KTcpSocket::ConnectedState);
    s .waitForReadyRead(2500);
    //I actually assume that the page delivered by www.iana.org will exist for years
    QVERIFY(s .bytesAvailable() > 200);

    s .write(HTTPREQUEST);
    s .waitForReadyRead();
    s .close();
    if (s .state() == KTcpSocket::ClosingState)
        s .waitForDisconnected(); } else { QCOMPARE (s .state (), KTcpSocket ::UnconnectedState); qDebug () << s .errorString (); }
    //What happens is that during waitForReadyRead() the write buffer is written out
    //completely so that the socket can shut down without having to wait for writeout.
    QCOMPARE(s .state(), KTcpSocket::UnconnectedState);

}

  1. /home/abuild/rpmbuild/BUILD/kdelibs-4.10.5/build/kdecore/tests/ktcpsockettest.shell

Actual Results:  
  1. 44: QDEBUG : KTcpSocketTest::statesIana() "Unknown error"

Expected Results:  
  1. 44: QDEBUG : KTcpSocketTest::statesIana() "Host www.iana.org not found"