'yum clean all' doesn't delete /var/cache/yum/.../<inactive repository>

Issue

• Why yum clean all or yum clean cache is not cleaning all files in /var/cache/yum
  • after adding new channels and retiring previous ones
  • when having disabled repositories
• /var/cache/yum not empty after running clean all or clean cache with yum
• Why do I have to manually clean /var/cache/yum ?
• Why is yum clean all not deleting cache files from disabled repositories ?