$ git clone -n https://src.fedoraproject.org/rpms/diff-pdf.git /var/lib/mock/f40-build-783135-132738/root/chroot_tmpdir/scmroot/diff-pdf
Cloning into '/var/lib/mock/f40-build-783135-132738/root/chroot_tmpdir/scmroot/diff-pdf'...
$ git fetch origin 7ffe66373aaa36f42ab6946f9b673b160d3a0cf3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/diff-pdf
 * [new ref]         7ffe66373aaa36f42ab6946f9b673b160d3a0cf3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7ffe663 Update to 0.5.2.