$ git clone -n https://src.fedoraproject.org/rpms/rust-uu_dirname.git /var/lib/mock/f40-build-774041-127569/root/chroot_tmpdir/scmroot/rust-uu_dirname
Cloning into '/var/lib/mock/f40-build-774041-127569/root/chroot_tmpdir/scmroot/rust-uu_dirname'...
$ git fetch origin abcd95536f72a15122162c43d9ae22141cf8107b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-uu_dirname
 * [new ref]         abcd95536f72a15122162c43d9ae22141cf8107b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at abcd955 Initial package (rhbz#2257499)