Fix error: Failed dependencies

Step 2 : RUN rpm -Uvh
http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
 ---> Running in 77c9aaf9947f
warning: /var/tmp/rpm-tmp.LayGgj: Header V3 RSA/SHA256 Signature, key ID
0608b895: NOKEY
error: Failed dependencies:
        fedora-release conflicts with epel-release-6-8.noarch
Retrieving
http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
2014/12/09 21:12:45 The command [/bin/sh -c rpm -Uvh
http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm]
returned a non-zero code: 1
[ubuntu@docker:~/docker-sensu-server(emacsupgrade)]$