401 under CentOS with absolute locations

The problem described in https://code.google.com/p/nexus-yum-plugin/issues/detail?id=17 does still exist, because CentOS does not support to force authentication on all URLs with the properties "password" and "username"(http://www.centos.org/docs/5/html/5.1/Deployment_Guide/s1-yum-yumconf-repository.html). Therefore we get a 401 whenever Yum tries to download one specific artifact, because the URL in the metadata delivered from the Nexus contains the host as well and therefore the baseurl from the yum repository configuration is not used (which is the only place where I could provide the credentials).