`sub-fonts-dir` doesn't work correctly

mpv Information

mpv v0.39.0 Copyright © 2000-2024 mpv/MPlayer/mplayer2 projects
 built on Nov 27 2024 18:31:26
libplacebo version: v7.349.0
FFmpeg version: n7.1
FFmpeg library versions:
   libavcodec      61.19.100
   libavdevice     61.3.100
   libavfilter     10.4.100
   libavformat     61.7.100
   libavutil       59.39.100
   libswresample   5.3.100
   libswscale      8.3.100

Other Information

- Linux version: Arch Linux
- Kernel Version: Linux akii 6.12.3-arch1-1 #1 SMP PREEMPT_DYNAMIC Fri, 06 Dec 2024 11:15:43 +0000 x86_64 GNU/Linux
- GPU Model: AMD Radeon RX 7900XTX
- Mesa/GPU Driver Version: 24.3.1
- Window Manager and Version: GNOME mutter 47.3
- Source of mpv: Arch Linux repository
- Latest known working version: 0.38.0
- Issue started after the following happened: Update mpv to 0.39.0

Reproduction Steps

1. Save a subtitle file to the folder Subs, it in the same directory as the video file.
2. Save some fonts to the folder Fonts, it in the same directory as the video file.
3. Run mpv --no-config --sub-auto=fuzzy --sub-file-paths=Subs --sub-fonts-dir=Fonts 'VIDEO_PATH' in terminal (pwd doesn't in the directory of the video file)
4. MPV doesn't load fonts from the Fonts folder.

Expected Behavior

MPV loads fonts from the folder Fonts like loads subtitles from the folder Subs.

Actual Behavior

MPV loads subtitles from the folder Subs, but it doesn't load fonts from the folder Fonts

Log File

in-video-folder.txt
not-in-video-folder.txt

Sample Files

No response

I carefully read all instruction and confirm that I did the following:

• I tested with the latest mpv version to validate that the issue is not already fixed.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.

Start by reproducing the command with --sub-auto=fuzzy, --sub-file-paths=Subs, and --sub-fonts-dir=Fonts from outside the video directory, then compare the two attached logs. Trace how the two path options resolve their directories; done means fonts load from Fonts just as subtitles load from Subs.