Unfortunately I didn't think ahead, and left no room in the version
numbering between 1.6.1 (for Varnish 6.1) and 1.6.2 (for 6.2). So
the package for this version will be released as 1.6.1-2. But now
we have more than one version in the history that announces itself
as 1.6.1.

The RPM spec strictly requires Varnish 6.1.