Revert "playbin2: Only allow to set the URIs in states <= READY or from an...
Revert "playbin2: Only allow to set the URIs in states <= READY or from an about-to-finish signal handler" This reverts commit 7335ce5d. Support abusing the uri property to configure the next uri to play outside of the about-to-finish handler for the time being after all. We also shouldn't use thread private structures for this, since it should be possible to block the thread that emitted about-to-finish while the main thread sets the uri property. See #607226.