Comment 63 for bug 1717040

b) artful package upgrade tests - PASS
Starting with the original artful packages:
dpubuntu@artful-zstd:~$ dpkg -l|grep zstd
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 pulls in no new packages and just upgrades the ones I have already:
The following packages will be upgraded:
  libzstd-dev libzstd1 zstd
3 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

resulting in:
ubuntu@artful-zstd:~$ dpkg -l|grep zstd
ii libzstd-dev 1.3.1+dfsg-1ubuntu0.1 amd64 fast lossless compression algorithm -- development files
ii libzstd1 1.3.1+dfsg-1ubuntu0.1 amd64 fast lossless compression algorithm
ii zstd 1.3.1+dfsg-1ubuntu0.1 amd64 fast lossless compression algorithm -- CLI tool

installing the libzstd1-dev transitional package:
ubuntu@artful-zstd:~$ sudo apt install libzstd1-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  libzstd1-dev
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.

removing libzstd-dev removes the transitional package:
ubuntu@artful-zstd:~$ sudo apt purge libzstd-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  libzstd-dev* libzstd1-dev*
0 upgraded, 0 newly installed, 2 to remove and 0 not upgraded.

installing the transitional package pulls in the unversioned dev package:
ubuntu@artful-zstd:~$ sudo apt install libzstd1-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  libzstd-dev
The following NEW packages will be installed:
  libzstd-dev libzstd1-dev