$ git clone -n https://src.fedoraproject.org/rpms/rust-curve25519-dalek.git /var/lib/mock/f40-build-1474581-23785/root/chroot_tmpdir/scmroot/rust-curve25519-dalek
Cloning into '/var/lib/mock/f40-build-1474581-23785/root/chroot_tmpdir/scmroot/rust-curve25519-dalek'...
$ git fetch origin 128f39100d6b303a7e44ec7285476db8b81100b9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-curve25519-dalek
 * [new ref]         128f39100d6b303a7e44ec7285476db8b81100b9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 128f391 Update to version 4.1.3; Fixes RHBZ#2292990