I don't know that it's expected, but it doesn't appear to be unexpected.  regrtest doesn't appear to know anything about expected failures or unexpected successes, mostly because both concepts appear at the individual test level while regrtest deals at the test module level.  unittest docs don't actually say what happens when an expected failure fails to fail.

As for this issue, it looks like the skipping of the test predates _have_soundcard and has_sound.  If there are no objections, I'll try the attached patch on default; if it causes failures, I'll try a 'skipUnless(has_sound('SystemDefault')...', and if that work's I'll backport it to the other two branches.