head: Ignore known-failing tests introduced in #1579

[nicoonoclaste]

This caused tests to fail on all unrelated work.
In particular, CI went red for all pull requests.

[rivy]

I think this was overly broad.
From looking at the CI output, it looks like only the 'test_head::test_bug_in_negative_zero_lines' test was failing.
Likely, just disabling that test one test would have fixed the issue.
How about re-enabling the others?

[nicoonoclaste]

@rivy I've uncountered test failures involving test_bug_in_negative_zero_lines, test_spams_newline, test_unsupported_byte_syntax, and test_unsupported_zero_terminated_syntax. Given the large number of failing tests (at least 4 out of 7 that I observed directly), and the seemingly unreliable nature of those failures, it seemed best not to second-guess the PR's author (who said all those test were failing against uutils' implementation of head)

[rivy]

Hmm, I never any of those errors in the CI builds. I didn't review the PR that added these tests, but, yes, if the PR author was including tests that are known to fail, they should be marked as ignore and future fix.

I'll go ahead and mark the tests as future 'FixME'. If there are any logs, I'd like to include them as helpful info for fixes.

Thanks for your review and help.