can't build docs for qtbase on dev branch - failure while creating index

cd qt5-dbg/qtbase/src/corelib

QT_INSTALL_DOCS=/home/rutledge/dev/qt5/qtbase/doc QT_VERSION_TAG=540 QT_VER=5.4 QT_VERSION=5.4.0 QT_PLUGIN_PATH=/home/rutledge/dev/qt5-dbg/qtbase/plugins LD_LIBRARY_PATH=/home/rutledge/dev/qt5-dbg/qtbase/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} /home/rutledge/dev/qt5-dbg/qtbase/bin/qdoc -outputdir /home/rutledge/dev/qt5-dbg/qtbase/doc/qtcore -installdir /home/rutledge/dev/qt5-dbg/qtbase/doc /home/rutledge/dev/qt5/qtbase/src/corelib/doc/qtcore.qdocconf -prepare -no-link-errors
Dependent modules specified, but no index directories were set. There will probably be errors for missing links.
void QXmlStreamWriter::writeAttribute(const QString&, const QString&) "/home/rutledge/dev/qt5-dbg/qtbase/doc/qtcore/qtcore.index" "typedef" "Qt::ApplicationStates"
ASSERT: "d->inStartElement" in file /home/rutledge/dev/qt5/qtbase/src/corelib/xml/qxmlstream.cpp, line 3421

void QXmlStreamWriter::writeAttribute(const QString &qualifiedName, const QString &value)
{
    Q_D(QXmlStreamWriter);
    if (!d->inStartElement) {
        QFile *f = static_cast<QFile *>(d->device);
        qDebug() << Q_FUNC_INFO << f->fileName() << qualifiedName << value;
    }
    Q_ASSERT(d->inStartElement);
...
}