If we use "Conflicts: otherproviders(%{name}-branding)" for packages, we get
RPMLINT warning in Tumbleweed and openSUSE Leap 15.1 builds, for example in 
https://build.opensuse.org/package/show/openSUSE%3AFactory/MozillaFirefox (and
in https://build.opensuse.org/package/show/mozilla/firefox69 )

MozillaFirefox-branding-upstream.i686: W: suse-branding-missing-conflicts
MozillaFirefox-branding
Any branding flavor package that provides the generic branding must also
conflict with all other branding packages via conflict on the generic branding
name

If we set "Conflicts: %{name}-branding", we no longer see such warning. However
using "Conflicts: %{name}-branding" contradicts with requirement to specify
"Provides: %{name}-branding". 


There was no such warning in openSUSE Leap 15.0. Thus seems there is regression
from openSUSE Leap 15.0.