Four more tests in the same family as the /tmp ones this change already
fixes, and they hide for the same reason: the failure depends on how
long $TMPDIR happens to be.
tests/test_shell_routes.py::TestHostDockerAccess (three) and
tests/test_cookbook_docker_access.py::test_container_opt_in_with_unix_
socket_is_allowed each bind an AF_UNIX socket at tmp_path/"docker.sock".
macOS gives sun_path 104 bytes including the terminator. pytest roots
tmp_path at $TMPDIR, which on a stock Mac is a 49-character
/var/folders/<2>/<30>/T/; add pytest-of-<user>/pytest-<n>/ and the
test's own name and the bind path is 115 bytes before the filename.
OSError: AF_UNIX path too long
Linux allows 108 and roots $TMPDIR at /tmp, so CI never sees it. Under a
shortened $TMPDIR the path lands at exactly 103 and passes — until
pytest's run counter reaches two digits and it becomes 104. That is why
the ledger's counts did not include these: they were measured somewhere
the path fit.
Adds tests/helpers/unix_sockets.bound_unix_socket, which binds under a
short directory and asserts the length before it tries, so the next
socket fixture fails with a sentence rather than an errno. Records the
trap in KNOWN_FAILURES.md along with the instruction to re-measure with
the default $TMPDIR.
Léo