Format selection broken

[tree68505]

Please follow the guide below

• You will be asked some questions and requested to provide some information, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your issue (like this: [x])
• Use the Preview tab to see what your issue will actually look like

---

Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2019.01.23. If it's not, read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2019.01.23

Before submitting an issue make sure you have:

• At least skimmed through the README, most notably the FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones
• Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

---

The following sections concretize particular purposed issues, you can erase any section (the contents between triple ---) not applicable to your issue

---

If the purpose of this issue is a bug report, site support request or you are not completely sure provide the full verbose output as follows:

Add the -v flag to your command line you run youtube-dl with (youtube-dl -v <your command line>), copy the whole output and insert it here. It should look similar to one below (replace it with your log inserted between triple ```):

[debug] System config: [u'-f', u'(bestvideo+bestaudio/best)[ext!=webm]', u'--restrict-filenames', u'--no-part', u'-o', u'***', u'--cookies', u'***']
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'--mark-watched', u'https://www.youtube.com/playlist?list=WL']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2019.01.23
[debug] Python version 2.7.13 (CPython) - Linux-4.9.0-8-amd64-x86_64-with-debian-9.6
[debug] exe versions: ffmpeg 3.2.12-1, ffprobe 3.2.12-1
[debug] Proxy map: {}
[youtube:watchlater] WL: Downloading webpage
[download] Downloading playlist: Watch Later Playlist
[youtube:watchlater] playlist Watch Later Playlist: Downloading 3 videos
[download] Downloading video 1 of 3
[youtube] ***: Downloading webpage
[youtube] ***: Downloading video info webpage
[youtube] ***: Marking watched
ERROR: requested format not available
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 804, in extract_info
    return self.process_ie_result(ie_result, download, extra_info)
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 858, in process_ie_result
    return self.process_video_result(ie_result, download=download)
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 1631, in process_video_result
    expected=True)
ExtractorError: requested format not available

---

Description of your issue, suggested solution and other information

The previously valid format selection of (bestvideo+bestaudio/best)[ext!=webm] no longer is valid since yesterday's release. Removing the [ext!=webm] avoids the error and shows it was rejecting a video of mp4 video and m4a audio [link]. After commit 2cc779f, != looks like it should still be valid per the updated documentation.

[tree68505]

Noticed that the unit tests don't rule out that the negation change doesn't just reject everything.