FairPlay: AVPlayerItem erratic status changes when errors encountered by its AVAssetResourceLoaderDelegate

[defagos]

When using a custom AVAssetResourceLoaderDelegate for FairPlay resource loading, and if loading fails (easy to simulate by having a resource loader immediately finish the loading request with an error), the player item suffers from erratic status changes. As a result, AVPlayerViewController or SRGMediaPlayerController get confused:

• An error is not immediately returned to the parent player.
• The skd resource loading process is made twice (and fails twice, of course).

When using the exact same resource loader, but with a standard HTTP stream, the behavior is correct, and the players do not get confused.

• The error is immediately returned to the player (though the original error information itself is lost, see Content protection errors are never forwarded to AVPlayer #3)
• Resource loading takes place only once.

This is probably an AVFoundation bug which should be reported to Apple.