$ git clone -n https://src.fedoraproject.org/rpms/R-stringdist.git /var/lib/mock/f42-build-side-1-3501293-45974/root/chroot_tmpdir/scmroot/R-stringdist
Cloning into '/var/lib/mock/f42-build-side-1-3501293-45974/root/chroot_tmpdir/scmroot/R-stringdist'...
$ git fetch origin 26cb3e9cc7ab00e0c9e5fe13fabef3635fadf3fb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-stringdist
 * [new ref]         26cb3e9cc7ab00e0c9e5fe13fabef3635fadf3fb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 26cb3e9 R-maint-sig mass rebuild