OpenStreetMap licenses are inconsistent

Right now, there are three different licenses for OpenStreetMap data:

 * Our own source claims that it's [CC-SA-2.0](https://github.com/openlayers/ol3/blob/master/src/ol/source/openstreetmapsource.js#L14)
 * Stamen thinks that it's [CC-SA-3.0](http://maps.stamen.com/#watercolor/12/37.7706/-122.3782) (scroll down to "How to Use These Tiles Elsewhere / COPY HTML)
 * OpenCycleMap thinks that it's [ODbL](http://opencyclemap.org/) (see attribution and link in bottom left corner)

At least two of these three are wrong. Who's correct? The [OpenStreetMap copyright page](http://www.openstreetmap.org/copyright) would suggest that it's OpenCycleMap.

Does anybody actually know?