Cannot play track when restoring playback state

[kingosticks]

Originally reported by @simmel at #146 (comment)

kaka:~$ mopidy
INFO     Starting Mopidy 2.1.0
INFO     Loading config from builtin defaults
INFO     Loading config from /Users/simlu/.config/mopidy/mopidy.conf
INFO     Loading config from command line options
INFO     Enabled extensions: spotify, mpd, http, stream, m3u, scrobbler, softwaremixer, file, local, local-sqlite
INFO     Disabled extensions: none
INFO     Starting Mopidy mixer: SoftwareMixer
INFO     Starting Mopidy audio
INFO     Starting Mopidy backends: StreamBackend, M3UBackend, FileBackend, LocalBackend, SpotifyBackend
INFO     Loaded 4512 local tracks using sqlite
INFO     Audio output set to "autoaudiosink"
INFO     Starting Mopidy core
INFO     Logged in to Spotify in offline mode
INFO     Loading state from /Users/simlu/.local/share/mopidy/core/state.json.gz
INFO     Playback of spotify:track:6g1NlCpW7fgqDnWbCCDrHl failed: Session must be logged in and online to load objects: <ConnectionState.OFFLINE: 4>
WARNING  Track is not playable: spotify:track:6g1NlCpW7fgqDnWbCCDrHl
INFO     Starting Mopidy frontends: MpdFrontend, HttpFrontend, ScrobblerFrontend
INFO     MPD server running at [::1]:6600
INFO     HTTP server running at [::ffff:127.0.0.1]:6680
INFO     Starting GLib mainloop
INFO     Logged in to Spotify in online mode
INFO     New MPD connection from [::1]:58387
INFO     Scrobbler connected to Last.fm
^CINFO     Interrupted. Exiting...
INFO     Stopping Mopidy frontends
INFO     Stopping Mopidy core
INFO     Saving state to /Users/simlu/.local/share/mopidy/core/state.json.gz
INFO     Limiting history to 500 tracks
INFO     Stopping Mopidy backends
INFO     Stopping Mopidy audio
INFO     Stopping Mopidy mixer

It looks to be due to a race condition as described here.