Решение проблемы с обновлением репозитория atomic в CentOS 6.5

warning: rpmts_HdrFromFdno: Header V3 RSA/SHA1 Signature, key ID 4520afa9: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY.art.txt

The GPG keys listed for the "CentOS / Red Hat Enterprise Linux 6 - atomicrocketturtle.com" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.
yum update atomic-release
yum upgrade
Если не помогло, то
get -q -O - https://www.atomicorp.com/installers/atomic | sh