Failed build log: https://copr-be.cloud.fedoraproject.org/results/praiskup/rpm-config/fedora-23-x86_64/00108212-compat-rpm-config/mockchain.log.gz Package 'compat-rpm-macros' needs to be installed before the SRPM is generated, otherwise some SPEC macros are not defined. Not sure whether the SRPM shouldn't be generated in mock too. This used to work (it is kind of usage regression) because (a) srpm was not generated from dist-git before.
You should use those macros conditionally. E.g. %{?scl_prefix} Otherwise somebody else would not be able to generate that SRPM too. And then you should include that package with macros in build time of binary RPM. Which is doable in Copr for months.