Without this patch, tests would fail on IPv6 hosts with this
mysterious error:
```
_______________________________________________________________________ TestHttpMisc.test_html ________________________________________________________________________
tests/checker/test_http_misc.py:30: in test_html
self.obfuscate_test()
tests/checker/test_http_misc.py:51: in obfuscate_test
url = u"http://%s/" % iputil.obfuscate_ip(ip)
linkcheck/network/iputil.py:290: in obfuscate_ip
raise ValueError('Invalid IP value %r' % ip)
E ValueError: Invalid IP value '2a02:2e0:3fe:1001:7777:772e:2:85'
```
As it turns out, the test host (`www.heise.de`) does have an IPv6
record and our tests pass on Travis only because they do not have a
working IPv6 stack. I happen to have IPv6 at home and tests are broken
here, so add a quick workaround so tests pass again.
Ideally, we would not have to deal with this hack and would handle
"obfuscation" correctly, but I have yet to figure out what that test
actually does before fixing it properly.
The test unzipps a zip file with a weird-looking non-ASCII filename in it.
I don't think zip files specify the encoding for filenames. Different
unzip utilities may interpret the filename differently. Plus, the byte
representation of the unzipped filename may be different depending on
the filesystem charset.
To me it looks as if the filename is garbage encoded as valid UTF-8, and
the test expectation is to get it in latin-1 or something.
The HTML tag has two attributes with URLs:
<applet archive="file.html" src="file.css">
It would appear that the order in which these attributes are crawled
does not match the order in the result file.
Possibly the crawling order is non-deterministic, although I cannot
reproduce that. If that's the case, the fix would be to sort the
attributes in the crawler before following them, which means we want the
expected results sorted as well (and since 'archive' comes before 'src',
so file.html should come before file.css).
