ffmpeg version is newer than expected

[zanymuzik]

Step 4/11 : RUN echo "deb http://www.deb-multimedia.org buster main non-free" >> /etc/apt/sources.list && apt-get update -oAcquire::AllowInsecureRepositories=true && apt-get install -y --allow-downgrades --allow-remove-essential --allow-change-held-packages --allow-unauthenticated deb-multimedia-keyring && apt-get install -y --allow-downgrades --allow-remove-essential --allow-change-held-packages --allow-unauthenticated ffmpeg=10:4.1.4-dmo1+deb10u1
---> Running in cda393dfa3da
Hit:1 http://security.debian.org/debian-security buster/updates InRelease
Hit:2 http://deb.debian.org/debian buster InRelease
Hit:3 http://deb.debian.org/debian buster-updates InRelease
Get:4 http://www.deb-multimedia.org buster InRelease [19.5 kB]
Ign:4 http://www.deb-multimedia.org buster InRelease
Get:5 http://www.deb-multimedia.org buster/main amd64 Packages [124 kB]
Get:6 http://www.deb-multimedia.org buster/non-free amd64 Packages [2480 B]
Fetched 146 kB in 2s (78.5 kB/s)
Reading package lists...
W: GPG error: http://www.deb-multimedia.org buster InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5C808C2B65558117
W: The repository 'http://www.deb-multimedia.org buster InRelease' is not signed.
Reading package lists...
Building dependency tree...
Reading state information...
The following NEW packages will be installed:
deb-multimedia-keyring
0 upgraded, 1 newly installed, 0 to remove and 4 not upgraded.
Need to get 10.7 kB of archives.
After this operation, 25.6 kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
deb-multimedia-keyring
Authentication warning overridden.
Get:1 http://www.deb-multimedia.org buster/main amd64 deb-multimedia-keyring all 2016.8.1 [10.7 kB]
debconf: delaying package configuration, since apt-utils is not installed
Fetched 10.7 kB in 0s (32.8 kB/s)
Selecting previously unselected package deb-multimedia-keyring.
(Reading database ... 26975 files and directories currently installed.)
Preparing to unpack .../deb-multimedia-keyring_2016.8.1_all.deb ...
Unpacking deb-multimedia-keyring (2016.8.1) ...
Setting up deb-multimedia-keyring (2016.8.1) ...
Reading package lists...
Building dependency tree...
Reading state information...
E: Version '10:4.1.4-dmo1+deb10u1' for 'ffmpeg' was not found