ARTFUL starting with all zstd packages installed: ii libzstd-dev 1.3.1+dfsg-1 amd64 fast lossless compression algorithm -- development files ii libzstd1 1.3.1+dfsg-1 amd64 fast lossless compression algorithm ii zstd 1.3.1+dfsg-1 amd64 fast lossless compression algorithm -- CLI tool dist-upgrade: The following packages will be upgraded: libzstd-dev libzstd1 zstd 3 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. results in: ii libzstd-dev 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm -- development files ii libzstd1 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm ii zstd 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm -- CLI tool installing libzstd1-dev: The following NEW packages will be installed: libzstd1-dev 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. removing libzstd-dev also removes libzstd1-dev: The following packages will be REMOVED: libzstd-dev* libzstd1-dev* 0 upgraded, 0 newly installed, 2 to remove and 0 not upgraded. installing just the new libzstd1-dev: The following additional packages will be installed: libzstd-dev libzstd1 The following NEW packages will be installed: libzstd-dev libzstd1 libzstd1-dev 0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded. RELEASE UPGRADE TO BIONIC a) with all zstd packages installed: ii libzstd-dev 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm -- development files ii libzstd1 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm ii libzstd1-dev 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 transitional package for libzstd-dev ii zstd 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm -- CLI tool do-release-upgrade stats: upgrade list: libzstd-dev libzstd1 libzstd1-dev zstd nothing else end result in bionic: ii libzstd-dev 1.3.3+dfsg-1ubuntu1~ppa1 amd64 fast lossless compression algorithm -- development files ii libzstd1 1.3.3+dfsg-1ubuntu1~ppa1 amd64 fast lossless compression algorithm ii libzstd1-dev 1.3.3+dfsg-1ubuntu1~ppa1 amd64 transitional package for libzstd-dev ii zstd 1.3.3+dfsg-1ubuntu1~ppa1 amd64 fast lossless compression algorithm -- CLI tool b) without the transitional package installed: ii libzstd-dev 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm -- development files ii libzstd1 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm ii zstd 1.3.1+dfsg-1ubuntu0.1~ppa3 amd64 fast lossless compression algorithm -- CLI tool do-release-upgrade stats: upgrade list: libzstd-dev libzstd1 zstd nothing else end result in bionic: ii libzstd-dev 1.3.3+dfsg-1ubuntu1~ppa1 amd64 fast lossless compression algorithm -- development files ii libzstd1 1.3.3+dfsg-1ubuntu1~ppa1 amd64 fast lossless compression algorithm ii zstd 1.3.3+dfsg-1ubuntu1~ppa1 amd64 fast lossless compression algorithm -- CLI tool