These two fields allow to specify a different default assignee for ticket opened against this package in bugzilla. Note: The EPEL field is always displayed for packages in the 'rpms' namespace regardless of whether it is used in bugzilla or not.
docker-common installs a script at /usr/bin/docker which will point to /usr/bin/docker-current by default. The docker daemon user could set the DOCKERBINARY variable in /etc/sysconfig/docker to point this to /usr/bin/docker-latest instead.