$ git clone -n https://src.fedoraproject.org/rpms/guestfs-tools.git /var/lib/mock/f40-build-768262-125260/root/chroot_tmpdir/scmroot/guestfs-tools
Cloning into '/var/lib/mock/f40-build-768262-125260/root/chroot_tmpdir/scmroot/guestfs-tools'...
$ git fetch origin 9743bac9b105008f42a037fbc3894667b5e502bb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/guestfs-tools
 * [new ref]         9743bac9b105008f42a037fbc3894667b5e502bb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9743bac New development version 1.51.7