tests fail with `--no-default-features`

[tenzap]

While trying to update space to 0.19 on Debian it appears the test suite is failing when invoked like this

$ cargo test --no-default-features 
   Compiling space v0.19.0 (/mnt/packages/git_repos/dpkg/debcargo-conf/build/space)
error[E0432]: unresolved import `space::linear_knn`
 --> tests/ndarray.rs:6:74
  |
6 | use space::{ApproximateSpace, ExactSpace, Knn, Metric, SpatialContainer, linear_knn, linear_nn};
  |                                                                          ^^^^^^^^^^
  |                                                                          |
  |                                                                          no `linear_knn` in the root
  |                                                                          help: a similar name exists in the module: `linear_nn`

For more information about this error, try `rustc --explain E0432`.
error: could not compile `space` (test "ndarray") due to 1 previous error