tests: running the tests with --no-default-features no longer works

[cakebaker]

When I try to run the tests of a single util with cargo test --features "cp" --no-default-features the tests of the util itself are no longer run. Instead, the failing of two other tests is shown:

failures:

---- util_completion stdout ----
thread 'util_completion' panicked at tests/test_util_name.rs:214:5:
assertion `left == right` failed
  left: Some(2)
 right: Some(0)

---- util_manpage stdout ----
thread 'util_manpage' panicked at tests/test_util_name.rs:242:5:
assertion `left == right` failed
  left: Some(2)
 right: Some(0)


failures:
    util_completion
    util_manpage

[sylvestre]

i guess it is #6198 by @BenWiederhake