2019-09-21 02:00:02,039 [INFO] {20704} koji.build.buildroot:505 Running mock as kojibuilder
INFO: mock.py version 1.4.14 starting (python version = 3.7.3)...
Start: init plugins
INFO: selinux enabled
Finish: init plugins
Start: run
Start: clean chroot
Finish: clean chroot
Start: chroot init
INFO: calling preinit hooks
INFO: enabled HW Info plugin
Mock Version: 1.4.14
INFO: Mock Version: 1.4.14
Start: dnf install
ERROR: Command failed: 
 # /usr/bin/dnf --installroot /var/lib/mock/f31-build-112037-34228/root/ --setopt=install_weak_deps=0 groupinstall build --setopt=tsflags=nocontexts
Unable to detect release version (use '--releasever' to specify release version)
Last metadata expiration check: 0:13:17 ago on Sat 21 Sep 2019 02:02:32 AM EDT.