$ git clone -n https://src.fedoraproject.org/rpms/rust-const_fn.git /var/lib/mock/f40-build-1971297-25220/root/chroot_tmpdir/scmroot/rust-const_fn
Cloning into '/var/lib/mock/f40-build-1971297-25220/root/chroot_tmpdir/scmroot/rust-const_fn'...
$ git fetch origin 8d2cdca368b99e56347e67b96d9740a81e256d31:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-const_fn
 * [new ref]         8d2cdca368b99e56347e67b96d9740a81e256d31 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8d2cdca Drop deny(warnings) from doctests to fix issues with Rust 1.80+