$ git clone -n https://src.fedoraproject.org/rpms/rubygem-cairo.git /var/lib/mock/f39-build-2073273-49357/root/chroot_tmpdir/scmroot/rubygem-cairo
Cloning into '/var/lib/mock/f39-build-2073273-49357/root/chroot_tmpdir/scmroot/rubygem-cairo'...
$ git fetch origin 1a98021c1e5d034ad8476cef895560ed667cf262:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-cairo
 * [new ref]         1a98021c1e5d034ad8476cef895560ed667cf262 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1a98021 1.17.13