PR#4271: Drop cvs requirement.

Merges #4271
https://pagure.io/koji/pull-request/4271

Fixes: #4265
https://pagure.io/koji/issue/4265
Drop explicit cvs requires?

docs/source/server_howto.rst

@@ -1220,6 +1220,13 @@ SCM checkout can contain multiple spec files (checkouted or created by
 ``source_cmd``). In such case spec file named same as a checkout directory will
 be selected.
 
+Supported SCMs are `git <https://git-scm.com/>`_ (base and over
+http/https/rsync), `Subversion <https://subversion.apache.org/>`_ (base and
+over http/https) and `CVS <https://www.nongnu.org/cvs/>`_ (base and over ssh).
+As CVS is the least used these days, it is now not installed by default on
+builders. If you need it, you've to ensure that ``cvs`` binary is available at
+the builders.
+
 .. note::
 
     We provide ``build_from_scm`` hub policy as an equivalent in version

koji.spec

@@ -281,7 +281,6 @@ Requires: squashfs-tools
 Requires(post): systemd
 Requires(preun): systemd
 Requires(postun): systemd
-Requires: /usr/bin/cvs
 Requires: /usr/bin/svn
 Requires: /usr/bin/git
 Requires: createrepo_c >= 0.11.0