$ git clone -n https://src.fedoraproject.org/rpms/rust-nu.git /var/lib/mock/f40-build-781387-131566/root/chroot_tmpdir/scmroot/rust-nu
Cloning into '/var/lib/mock/f40-build-781387-131566/root/chroot_tmpdir/scmroot/rust-nu'...
$ git fetch origin d7a00bd1abebe7f350c62a24e74db080a50b4159:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-nu
 * [new ref]         d7a00bd1abebe7f350c62a24e74db080a50b4159 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d7a00bd Tweak memory limits to allow build to succeed on all arches; drop ix86