weird failing abuild-tar tests

suddenly failed with no reason

===> tests/abuild_tar_test:abuild_tar_invalid_opt
Result:     failed: atf-check failed; see the output of the test for details
Start time: 2023-04-14T12:44:51.630852Z
End time:   2023-04-14T12:44:51.640380Z
Duration:   0.010s

Metadata:
    allowed_architectures is empty
    allowed_platforms is empty
    description is empty
    has_cleanup = false
    is_exclusive = false
    required_configs is empty
    required_disk_space = 0
    required_files is empty
    required_memory = 0
    required_programs is empty
    required_user is empty
    timeout = 300

Standard output:
Executing command [ abuild-tar --invalid ]

Standard error:
Fail: regexp usage: not in stderr
abuild-tar: unrecognized option: invalid
===> Failed tests
tests/abuild_tar_test:abuild_tar_invalid_opt  ->  failed: atf-check failed; see the output of the test for details  [0.010s]

not sure how this happens. manual abuild-tar correctly outputs usage to stderr..