$ git clone -n https://src.fedoraproject.org/rpms/mongo-c-driver.git /var/lib/mock/f42-build-862842-171168/root/chroot_tmpdir/scmroot/mongo-c-driver
Cloning into '/var/lib/mock/f42-build-862842-171168/root/chroot_tmpdir/scmroot/mongo-c-driver'...
$ git fetch origin e96a41394efac0c78b6f9e600070f69b1ada2975:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mongo-c-driver
 * [new ref]         e96a41394efac0c78b6f9e600070f69b1ada2975 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e96a413 update to 1.29.1