$ git clone -n https://src.fedoraproject.org/rpms/R-pdftools.git /var/lib/mock/f43-build-side-110352-58908153-6569187/root/chroot_tmpdir/scmroot/R-pdftools
Cloning into '/var/lib/mock/f43-build-side-110352-58908153-6569187/root/chroot_tmpdir/scmroot/R-pdftools'...
$ git fetch origin baedf70ecf044d79ea2e16ff4a8e6b76c58d65d6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-pdftools
 * [new ref]         baedf70ecf044d79ea2e16ff4a8e6b76c58d65d6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at baedf70 R-maint-sig mass rebuild