Cycling audio when playing an online video causes cache to be invalidated and the video has to be redownloaded again

Important Information

Provide following Information:

• mpv version

mpv v0.36.0-103-g455487bdc9 Copyright © 2000-2023 mpv/MPlayer/mplayer2 projects
 built on Aug 15 2023 22:25:24
libplacebo version: v5.264.1
FFmpeg version: n6.0
FFmpeg library versions:
   libavutil       58.2.100
   libavcodec      60.3.100
   libavformat     60.3.100
   libswscale      7.1.100
   libavfilter     9.3.100
   libswresample   4.10.100

• Platform and Version

Linux (Linux  6.4.12-arch1-1 #1 SMP PREEMPT_DYNAMIC Thu, 24 Aug 2023 00:38:14 +0000 x86_64 GNU/Linux)

• Source of the mpv binary
  Built from source.

Reproduction steps

1. Open an online video file: mpv --no-config -v -v https://www.youtube.com/watch\?v\=vpaPWuDQUcc
2. Once it starts playing, press pause so it can cache some video
3. Press the # key once to cycle the audio track. and you will see "No audio" displayed in OSD.
4. Press the # again to switch back to "Audio (eng)"
5. Notice how the cache was invalidated and the mpv is re-downloading the video all over again

Expected behavior

Please don't re-download the video just because an audio track was switched to a non-existing track.

Actual behavior

It deletes cache and re-downloads everything again.

Log file

Make a log file made with -v -v or --log-file=output.txt, paste it to
https://0x0.st/ or attach it to the github issue, and replace this text with a
link to it.

Sample files

n/a

Start by reproducing the issue with the provided mpv command and reviewing the linked verbose log. Trace the audio-track cycling path and cache invalidation behavior; done means switching to the nonexistent track and back no longer discards already cached video or re-downloads it.