This message will be printed relatively often once EOF is reached. In
some cases this is rather annoying, for example when playing HLS. (With
HLS, the stream is just a playlist file, while libavformat opens actual
media files without mpv's knowledge, so the cache is completely useless
and hits EOF instantly.)
That it retries reading is apparently a good thing: at least local files
can grow, and even after the player got the EOF, playback _could_ be
resumed by basically polling and detecting that there is more data. So
I'm not changing this behavior yet.