$ git clone -n https://src.fedoraproject.org/rpms/rust.git /var/lib/mock/f39-build-1736268-41260/root/chroot_tmpdir/scmroot/rust
Cloning into '/var/lib/mock/f39-build-1736268-41260/root/chroot_tmpdir/scmroot/rust'...
$ git fetch origin 6a528e91696ccebbb2a851ccec4e1e82ea543e10:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust
 * [new ref]         6a528e91696ccebbb2a851ccec4e1e82ea543e10 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6a528e9 Update to 1.74.0.