Comment 38 for bug 1717040

ARTFUL (details in the attached zstd-artful.txt file):

starting with:
libzstd-dev 1.3.1+dfsg-1
libzstd1 1.3.1+dfsg-1
zstd 1.3.1+dfsg-1

results in (no big deal):
libzstd-dev 1.3.1+dfsg-1ubuntu0.1~ppa2
libzstd1 1.3.1+dfsg-1ubuntu0.1~ppa2
zstd 1.3.1+dfsg-1ubuntu0.1~ppa2

installing the new libzstd1-dev transitional package changes nothing, as expected:
The following NEW packages will be installed:
  libzstd1-dev
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.

but 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.

and if you start from nothing and install libzstd1-dev (the transitional package);
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.

you also get the "real" dev package, and the actual library.

I'll do the same layout for bionic.