$ git clone -n https://src.fedoraproject.org/rpms/R-whoami.git /var/lib/mock/f43-build-58897687-6569095/root/chroot_tmpdir/scmroot/R-whoami
Cloning into '/var/lib/mock/f43-build-58897687-6569095/root/chroot_tmpdir/scmroot/R-whoami'...
$ git fetch origin 1505e51766f070d2b38a3a00c3a70050f6c2abcf:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-whoami
 * [new ref]         1505e51766f070d2b38a3a00c3a70050f6c2abcf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1505e51 R-maint-sig mass rebuild