$ git clone -n https://src.fedoraproject.org/rpms/R-webfakes.git /var/lib/mock/f41-build-710598-13019/root/chroot_tmpdir/scmroot/R-webfakes
Cloning into '/var/lib/mock/f41-build-710598-13019/root/chroot_tmpdir/scmroot/R-webfakes'...
$ git fetch origin 81c43436edfa4d2fbd96e036df3e3b7d7151b0ec:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-webfakes
 * [new ref]         81c43436edfa4d2fbd96e036df3e3b7d7151b0ec -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 81c4343 R-maint-sig mass rebuild