--write-thumbnail --output %(title)s ,doesn't have the behaviour

[Bepitic]

Checklist

• I'm reporting a broken site support issue
• I've verified that I'm running youtube-dl version 2019.11.28
• 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 -v --ignore-errors --write-thumbnail  --output "./%(title)s" https://www.youtube.com/watch\?v\=WsMqp85TtaM
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', '--ignore-errors', '--write-thumbnail', '--output', './%(title)s', 'https://www.youtube.com/watch?v=WsMqp85TtaM']
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dl version 2019.11.28
[debug] Python version 3.8.0 (CPython) - Linux-5.4.5-arch1-1-x86_64-with-glibc2.2.5
[debug] exe versions: ffmpeg 4.2.1, ffprobe 4.2.1
[debug] Proxy map: {}
[youtube] WsMqp85TtaM: Downloading webpage
[youtube] WsMqp85TtaM: Downloading video info webpage
[youtube] {18} signature length 108, html5 player vfl22ubNH
[youtube] {137} signature length 108, html5 player vfl22ubNH
[youtube] {248} signature length 104, html5 player vfl22ubNH
[youtube] {299} signature length 104, html5 player vfl22ubNH
[youtube] {303} signature length 104, html5 player vfl22ubNH
[youtube] {136} signature length 108, html5 player vfl22ubNH
[youtube] {247} signature length 104, html5 player vfl22ubNH
[youtube] {298} signature length 104, html5 player vfl22ubNH
[youtube] {302} signature length 108, html5 player vfl22ubNH
[youtube] {135} signature length 108, html5 player vfl22ubNH
[youtube] {244} signature length 108, html5 player vfl22ubNH
[youtube] {134} signature length 108, html5 player vfl22ubNH
[youtube] {243} signature length 108, html5 player vfl22ubNH
[youtube] {133} signature length 104, html5 player vfl22ubNH
[youtube] {242} signature length 104, html5 player vfl22ubNH
[youtube] {160} signature length 108, html5 player vfl22ubNH
[youtube] {278} signature length 104, html5 player vfl22ubNH
[youtube] {140} signature length 108, html5 player vfl22ubNH
[youtube] {249} signature length 108, html5 player vfl22ubNH
[youtube] {250} signature length 104, html5 player vfl22ubNH
[youtube] {251} signature length 108, html5 player vfl22ubNH
[debug] Default format spec: bestvideo+bestaudio/best
[youtube] WsMqp85TtaM: Downloading thumbnail ...
[youtube] WsMqp85TtaM: Writing thumbnail to: ./Tritan - Hollow Life (feat.jpg
[download] ./Tritan - Hollow Life (feat. Ratfoot) [NCS Release].webm has already been downloaded and merged

Description

Problem:
The files the command generates:
./Tritan - Hollow Life (feat.jpg
./Tritan - Hollow Life (feat. Ratfoot) [NCS Release].webm

The desire files:
./Tritan - Hollow Life (feat. Ratfoot) [NCS Release].jpg
./Tritan - Hollow Life (feat. Ratfoot) [NCS Release].webm

The template output %(title)s , doesn't have the same behaviour for thumbnails and video

[dstftw]

You must use ext in output template.