This function is not public and brooks (initial committer adding the code)
suggests the deletion of the tests (which I don't know if they work)
instead of changing the visibility of the function.
Four tests currently fail:
test_ether_line_bad_1() and test_ether_line_bad_2() due to bugs in
ether_line(3).
test_ether_ntohost() and test_ether_hostton() due to not being fully
implemented tests.