Cannot install QGIS 2.18 from repository on Debian Stretch; package "gdal-abi-2-1-1" not installable

I've been using QGIS from the repository (http://qgis.org/debian/ stretch main). I tried to do an update today (it had been a while) but it could not be updated because qgis : Depends: gdal-abi-2-1-1 but it is not installable.

I uninstalled QGIS, switched the repository to http://qgis.org/debian-nightly-release/, and tried to reinstall, but it gave me the same error.

 qgis : Depends: gdal-abi-2-1-1 but it is not installable
        Depends: libqgis-analysis2.18.0 but it is not going to be installed

        Depends: libqgis-app2.18.0 but it is not going to be installed
        Depends: python-qgis (= 1:2.18.0+git20161104+b23e29f+14stretch) but it is not going to be installed
        Recommends: qgis-plugin-globe but it is not going to be installed
        Recommends: qgis-plugin-grass but it is not going to be installed
        Recommends: qgis-provider-grass but it is not going to be installed

A bit of searching shows that this package is available in sid, but not stretch.