$ git clone -n https://src.fedoraproject.org/rpms/rubygem-comp_tree.git /var/lib/mock/f45-build-34880-692/root/chroot_tmpdir/scmroot/rubygem-comp_tree
Cloning into '/var/lib/mock/f45-build-34880-692/root/chroot_tmpdir/scmroot/rubygem-comp_tree'...
$ git fetch origin 298da76f5295231b87cd8951c62281d6311a5dc3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-comp_tree
 * [new ref]         298da76f5295231b87cd8951c62281d6311a5dc3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 298da76 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild