$ git clone -n https://src.fedoraproject.org/rpms/rust-der.git /var/lib/mock/f39-build-1488835-34499/root/chroot_tmpdir/scmroot/rust-der
Cloning into '/var/lib/mock/f39-build-1488835-34499/root/chroot_tmpdir/scmroot/rust-der'...
$ git fetch origin 3ebddbf70e2e3fb0d0d5327713817bf1b73617fa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-der
 * [new ref]         3ebddbf70e2e3fb0d0d5327713817bf1b73617fa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3ebddbf Update to version 0.7.8; Fixes RHBZ#2229840