Syncing EPEL 7 to a RHEL6-based Satellite

After creating an EPEL child channel in your satellite for EPEL7, and creating a repository definition to sync from, you may experience the following error from spacewalk-repo-sync:

Error: xz compression not available

This is because the new RHEL7 EPEL repository is created with XZ compressed repodata unlike other repos you've synced in the past. You must install the package 'pyliblzma' from EPEL6 onto your satellite in order to sync EPEL7.