Detect cyclic dependencies properly

Change-Id: I8d6e9cb358aa4b8c8f0bae34e21536219747884b
Reviewed-on: https://pirx.atteo.com/gerrit/561
Tested-by: Mr. Jenkins
Reviewed-by: Sławek Piotrowski <sentinel@atteo.com>
Explicitly defined config files are not optional

Change-Id: I3a0676b6113611567ae0436acfa27a21c974d824
Reviewed-on: https://pirx.atteo.com/gerrit/563
Tested-by: Mr. Jenkins
Reviewed-by: Sławek Piotrowski <sentinel@atteo.com>