perl-CPANPLUS includes the inc::Module::Install needed to build it but this is removed and a buildreq of perl(inc::Module::Install) is used instead. However, perl-Module-Install itself has a dependency on perl(CPANPLUS::Backend), which is provided by perl-CPANPLUS, thus creating a build dependency loop. This could be avoided by reverting the "unbundling" of inc::Module::Install from perl-CPANPLUS.
Sure. Once koji will get healthy, I'll do that.