`centos-release-gluster-legacy` removes unmaintained versions of
`centos-release-gluster*` packages from the system..

This package needs to get build by the CentOS core team that maintains the
Extras repository.

Building the package can be done like this:

    $ rpmbuild -bs \
               --define "_sourcedir $PWD/SOURCES" --define "_srcrpmdir $PWD" \
               --define "dist .el7.centos" \
               SPECS/centos-release-gluster-legacy.spec

    $ cbs build --scratch \
           storage7-gluster-9-el7 \
           centos-release-gluster-legacy-8-1.el7.centos.src.rpm