Hmmm, rpm-4.0.4 might now Do The Right Thing with Obsoletes: kdelock-splash i.e. erase any/all packages that have Provides: kdelock-splash
Be forewarned: The above *still* does not fix your problem, as any number of legacy versions of rpm are gonna be used to install your package, and the traditional behavior of rpm required a package name, not a virtual provide, in the OBSOLETENAME field.
Greetings, Jaco