$ git clone -n https://src.fedoraproject.org/rpms/R-hms.git /var/lib/mock/f42-build-3530687-46321/root/chroot_tmpdir/scmroot/R-hms
Cloning into '/var/lib/mock/f42-build-3530687-46321/root/chroot_tmpdir/scmroot/R-hms'...
$ git fetch origin 6983fb8a526e2701ac64b602f3e6f621b814a1b6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-hms
 * [new ref]         6983fb8a526e2701ac64b602f3e6f621b814a1b6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6983fb8 R-maint-sig mass rebuild