$ git clone -n https://src.fedoraproject.org/rpms/python-carbon.git /var/lib/mock/f45-build-29862-641/root/chroot_tmpdir/scmroot/python-carbon
Cloning into '/var/lib/mock/f45-build-29862-641/root/chroot_tmpdir/scmroot/python-carbon'...
$ git fetch origin 9925112eb6cf0ea8231a87814636fc9dd56fef8c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-carbon
 * [new ref]         9925112eb6cf0ea8231a87814636fc9dd56fef8c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9925112 Fix FTBFS (fedora#2504451).