Problems building cabal-install?

I am having a rather unexpected difficulty building older versions of cabal-install. The invariably run into conflicts between "Cabal" and "Cabal-syntax". The latter shows up as a dependency of "Cabal" on hackage, but not in the upstream Git repo. Is there is there some sort of problem with the hackage metadata for Cabal 3.0, 3.2, 3.4, ... It is odd for these to have "Cabal-syntax 3.10.*" as a dependency, with conflicting definitions. -- Viktor.