$ git clone -n https://src.fedoraproject.org/rpms/R-Rsolid.git /var/lib/mock/f42-build-side-1-3500768-45971/root/chroot_tmpdir/scmroot/R-Rsolid
Cloning into '/var/lib/mock/f42-build-side-1-3500768-45971/root/chroot_tmpdir/scmroot/R-Rsolid'...
$ git fetch origin 56af6fde783208c4a02e21ea5d29f2b439b82030:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-Rsolid
 * [new ref]         56af6fde783208c4a02e21ea5d29f2b439b82030 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 56af6fd R-maint-sig mass rebuild