I've just had to remove the Fedora (EPEL) perl-DateTime package and replace it with the rpmforge perl-DateTime package, to install some other rpmforge package that specified perl-DateTime had to be 0.17 or greater (I had 0.41 installed from EPEL).

On the CLI, I can install a package from a specific repo as follows:

--disablerepo=* --enablerepo=rpmforge

Contributed PR: https://github.com/cfengine/masterfiles/pull/1014, https://github.com/cfengine/masterfiles/pull/1069

Usage

bundle agent main
{
  packages:
    "git"
        policy => "present",
        package_module => yum,
        options => { "enablerepo=updates" };
}