Youtube: --all-subs doesn't download automatically generated transcripts: "video doesn't have subtitles"

[Geremia]

Checklist

• I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2020.01.24
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones

Verbose log

youtube-dl -v --skip-download --all-subs https://youtu.be/i4Rr5wXSXII
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', '--skip-download', '--all-subs', 'https://youtu.be/i4Rr5wXSXII']
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dl version 2020.01.24
[debug] Python version 3.8.1 (CPython) - Linux-5.4.19-x86_64-AMD_Ryzen_Threadripper_2990WX_32-Core_Processor-with-glibc2.2.5
[debug] exe versions: ffmpeg 4.2.1, ffprobe 4.2.1
[debug] Proxy map: {}
[youtube] i4Rr5wXSXII: Downloading webpage
[youtube] i4Rr5wXSXII: Downloading video info webpage
WARNING: video doesn't have subtitles
[debug] Default format spec: bestvideo+bestaudio/best

Description

--all-subs doesn't download automatically generated YouTube transcripts. The above command doesn't produce any subtitles files.

[Geremia]

@dstftw It should be complete now.