Broken terminal simulation tests / stty

[julian-klode]

In 0.2.2 these tests fail:

test_env::test_simulation_of_terminal_for_stdin_only
test_env::test_simulation_of_terminal_size_information
test_env::test_simulation_of_terminal_true

When rust-coreutils provide the stty command. The test cases by using a shell script inadvertently test the host-installed command, and the Rust version of stty prefers to use /dev/tty instead of /dev/stdin like the GNU one, thus querying the actual underlying tty instead of the simulated tty on stdin.

[ChrisDryden]

The shell script in question is this one: https://github.com/uutils/coreutils/blob/main/tests/fixtures/util/is_a_tty.sh Working on validating how to tell if we're using the GNU one or the uutils one in the tests.

[ChrisDryden]

The preference of /dev/tty changing to /dev/stdin was fixed in this PR: #9881

Now it should be okay even if the rust-coreutils version is the one thats used to run the tests. Please let me know if I misunderstood the issue, I'm making the assumption that its okay to use whichever version is in the path.