youtube:channel: fails with "This playlist does not exist."

[leonklingele]

Checklist

• I'm reporting a broken site support issue
• I've verified that I'm running youtube-dl version 2020.06.16.1
• 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 bug reports including closed ones
• I've read bugs section in FAQ

Verbose log

$ youtube-dl --verbose 'https://www.youtube.com/channel/UCQcTmBevae2jDeFEZ6VEQPw/videos'
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'--verbose', u'https://www.youtube.com/channel/UCQcTmBevae2jDeFEZ6VEQPw/videos']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 2.7.17 (CPython) - Darwin-15.6.0-x86_64-i386-64bit
[debug] exe versions: avconv 12.3, avprobe 12.3, ffmpeg 4.2.3, ffprobe 4.2.3, phantomjs 2.1.1, rtmpdump 2.4
[debug] Proxy map: {}
[youtube:channel] UCQcTmBevae2jDeFEZ6VEQPw: Downloading channel page
[youtube:playlist] UUQcTmBevae2jDeFEZ6VEQPw: Downloading webpage
ERROR: This playlist does not exist.
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 797, in extract_info
    ie_result = ie.extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 530, in extract
    ie_result = self._real_extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 2897, in _real_extract
    has_videos, playlist = self._extract_playlist(playlist_id)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 2820, in _extract_playlist
    raise ExtractorError(message, expected=True)
ExtractorError: This playlist does not exist.

Description

When downloading certain YouTube channels (i.e. all videos of it), youtube-dl fails with This playlist does not exist..
One such a channel is https://www.youtube.com/channel/UCQcTmBevae2jDeFEZ6VEQPw.