$ git clone -n https://src.fedoraproject.org/rpms/R-pdftools.git /var/lib/mock/f42-build-side-1-3562194-46722/root/chroot_tmpdir/scmroot/R-pdftools
Cloning into '/var/lib/mock/f42-build-side-1-3562194-46722/root/chroot_tmpdir/scmroot/R-pdftools'...
$ git fetch origin ba6e8e749e1c0ed56c7ace4d29fbf47c3215f7d6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-pdftools
 * [new ref]         ba6e8e749e1c0ed56c7ace4d29fbf47c3215f7d6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ba6e8e7 Merge branch 'rawhide' into f42