According to the folks at MPD the spotify plug in is depreciated and was removed in the latest Feb 6 update.
Music Player Daemon 0.19.9 has been released. It allows the dsdiff and dsf decoders to read larger ID3 tags and fixes loading duplicate tag types from the state file. The despotify plugin has been removed because the underlying third-party library is unmaintained and has been defunct for quite some time. Again, various rare build failures have been fixed.
Just a FYI for a potential problem in the future.