centos 7 testing image build fails when install epel rpm

[yedayak]

It seems that the epel-release-latest-7.noarch.rpm isn't available anymore from https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm, and presumably even if it did it won't work anymore since everything under https://dl.fedoraproject.org/pub/epel/7/ moved to https://dl.fedoraproject.org/pub/archive/epel/7/.

I think the solution should be to setup the epel repo manually without install the epel release rpm

Failing job

[scop]

Some other updates besides the EPEL changes are needed, and it seems we could get away with a couple of seds instead of a whole manual setup, so opted for that in #1369