$ git clone -n https://src.fedoraproject.org/rpms/rust-der_derive.git /var/lib/mock/f40-build-2072144-49334/root/chroot_tmpdir/scmroot/rust-der_derive
Cloning into '/var/lib/mock/f40-build-2072144-49334/root/chroot_tmpdir/scmroot/rust-der_derive'...
$ git fetch origin bb1d569ad60570e25704fa5d809ffafa14d969eb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-der_derive
 * [new ref]         bb1d569ad60570e25704fa5d809ffafa14d969eb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bb1d569 Update to version 0.7.2; Fixes RHBZ#2229830