I have started a thread on the epel-devel mailing list: https://firstname.lastname@example.org/thread/ICZGG2SQKUTV2JUBAS4XTWX2FQIKZT27/
I hope to get some replies that could gives us some direction.
This package is not installable.
Ok, this is where CentOS is just repackaging RHEL, so really this is a RHEL bug.
This is not a RHEL bug, you are trying to create the same package with a newer version number.
The cmake vs cmake3 split made sense in EPEL 7 where the base repos had CMake 2 and the EPEL repos had CMake 3. This does not make sense anymore, since the cmake package in the base repos already is version 3.
How does it make sense for there to be "cmake" and "cmake3" packages at the same time, when both are version 3?
The only right move here would be to create a module that contains the "cmake" package, but overrides the base version. This is exactly the situation that modules should be good for.