Nothing provides lzip

Hi, I stumbled over a strange error, e.g. for https://build.opensuse.org/package/show/devel:tools:scm/rcs For the repos 15.4 and 15.5, the build error is "Nothing provides lzip", although Leap 15.4 and Leap 15.5 both have this package available. And the spec file rcs.spec does list "BuildRequires: lzip" as needed. Does anybody have a clue what is going on? Thanks, Manfred