opening menu bgm in streaming mode causes decoding issues

[RiedleroD]

this is a bug in pyglet, but I'll add it anyway so I can fix it if a workaround is found

code sample to reproduce:

import pyglet
from pyglet.media.codecs.ffmpeg import FFmpegDecoder
dec=FFmpegDecoder()
mus=pyglet.media.load("./mus.wav",streaming=True,decoder=dec)
pl=mus.play()
pl.loop=True
pyglet.app.run()

This only happens when FFmpegDecoder is selected in streaming mode and the player loops. Incredibly specific, but all of those are necessary, since:

• only ffmpeg supports opus, Gstreamer is not compatible.
• it's the menu bgm, ofc it should loop.
• not streaming music causes long loading startup
  Since I don't have a choice here, I disabled streaming in the default datapack anyway.