"apt install foo/bar" will try to satisfy dependencies of foo from release bar if the current candidates do not satisfy the requirements. That is more a feature for going to a PPA (or backports) than leaving it and has some issues, but it exists (e.g. your downgrade has probably all dependencies satisfied by the already installed [newer] versions from the PPA).
Note that downgrades are still unsupported and can break your system, so that is really not a painless action. Nobody said activating PPAs left and right is something you can or should do – or that it is easy to change your might. You probably want something like "pick all packages from PPA foo and install from bar". I think you can express something like that with the newish patterns, but note that apt doesn't really know if a package was installed from PPA foo. It guesses that if the current version is the same as the version in the PPA it was installed from there, but that isn't the same thing… -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apt in Ubuntu. https://bugs.launchpad.net/bugs/1857018 Title: apt-get: Can not downgrade dependencies or anything with -t Status in apt package in Ubuntu: Invalid Bug description: Only the latter command downgrades the mythtv-frontend package (after removing the PPA from /etc/apt/sources.list.d/ and running 'apt update'): $ sudo apt-get install mythtv-frontend -s -V -t bionic Reading package lists... Done Building dependency tree Reading state information... Done mythtv-frontend is already the newest version (2:30.0+fixes.201912012038.a27754a~ubuntu18.04.1). 0 upgraded, 0 newly installed, 0 to remove and 8 not upgraded. $ sudo apt-get install mythtv-frontend/bionic -s -V Reading package lists... Done Building dependency tree Reading state information... Done Selected version '2:29.1+fixes.20180414.329c235-0ubuntu3' (Ubuntu:18.04/bionic [amd64]) for 'mythtv-frontend' Suggested packages: mythtv-backend (2:29.1+fixes.20180414.329c235-0ubuntu3) mythmusic (2:29.1+fixes.20180414.329c235-0ubuntu3) mythweather (2:29.1+fixes.20180414.329c235-0ubuntu3) mythgallery (2:29.1+fixes.20180414.329c235-0ubuntu3) mythgame (2:29.1+fixes.20180414.329c235-0ubuntu3) The following packages will be REMOVED: mythtv-dbg (2:30.0+fixes.201912012038.a27754a~ubuntu18.04.1) The following packages will be DOWNGRADED: mythtv-frontend (2:30.0+fixes.201912012038.a27754a~ubuntu18.04.1 => 2:29.1+fixes.20180414.329c235-0ubuntu3) 0 upgraded, 0 newly installed, 1 downgraded, 1 to remove and 4 not upgraded. Remv mythtv-dbg [2:30.0+fixes.201912012038.a27754a~ubuntu18.04.1] Inst mythtv-frontend [2:30.0+fixes.201912012038.a27754a~ubuntu18.04.1] (2:29.1+fixes.20180414.329c235-0ubuntu3 Ubuntu:18.04/bionic [amd64]) Conf mythtv-frontend (2:29.1+fixes.20180414.329c235-0ubuntu3 Ubuntu:18.04/bionic [amd64]) I do not know, if there is a reason for the different behavior. Anyway, I want to be able to easily downgrade the depending packages, too, retaining their auto/manual status. ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: apt 1.6.12 ProcVersionSignature: Ubuntu 5.0.0-37.40~18.04.1-generic 5.0.21 Uname: Linux 5.0.0-37-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.20.9-0ubuntu7.9 Architecture: amd64 CurrentDesktop: XFCE Date: Thu Dec 19 16:25:51 2019 InstallationDate: Installed on 2019-05-08 (224 days ago) InstallationMedia: Xubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210) SourcePackage: apt UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1857018/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
