$ git clone -n https://src.fedoraproject.org/rpms/R-pdftools.git /var/lib/mock/f40-build-1944506-25177/root/chroot_tmpdir/scmroot/R-pdftools
Cloning into '/var/lib/mock/f40-build-1944506-25177/root/chroot_tmpdir/scmroot/R-pdftools'...
$ git fetch origin bd30c0046e5fc04896df4e0cec5e00c624b2d815:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-pdftools
 * [new ref]         bd30c0046e5fc04896df4e0cec5e00c624b2d815 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bd30c00 R-maint-sig mass rebuild