WPT nightly sync is busted

[jdm]

Error running mach:
    ['test-wpt', '--release', '--processes', '12', '--log-raw', 'test-wpt.log', '--always-succeed']
The error occurred in code that was called by the mach command. This is either
a bug in the called code itself or in the way that mach is calling it.
You can invoke |./mach busted| to check if this issue is already on file. If it
isn't, please use |./mach busted file| to report it. If |./mach busted| is
misbehaving, you can also inspect the dependencies of bug 1543241.
If filing a bug, please include the full output of mach, including this error
message.
The details of the failure are as follows:
AssertionError
  File "/repo/python/servo/testing_commands.py", line 398, in test_wpt
    ret = self.run_test_list_or_dispatch(kwargs["test_list"], "wpt", self._test_wpt, **kwargs)
  File "/repo/python/servo/testing_commands.py", line 429, in run_test_list_or_dispatch
    return correct_function(**kwargs)
  File "/repo/python/servo/testing_commands.py", line 424, in _test_wpt
    return self.wptrunner(run_file, **kwargs)
  File "/repo/python/servo/testing_commands.py", line 468, in wptrunner
    return run_globals["run_tests"](**kwargs)
  File "/repo/tests/wpt/run.py", line 52, in run_tests
    success = wptrunner.run_tests(**kwargs)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptrunner.py", line 183, in run_tests
    **kwargs)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptrunner.py", line 84, in get_loader
    chunker_kwargs=chunker_kwargs)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/testloader.py", line 205, in __init__
    self._load_tests()
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/testloader.py", line 268, in _load_tests
    for test_path, test_type, test in self.iter_tests():
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/testloader.py", line 261, in iter_tests
    yield test_path, test_type, self.get_test(manifest_file, test, inherit_metadata, test_metadata)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/testloader.py", line 221, in get_test
    return wpttest.from_manifest(manifest_file, manifest_test, inherit_metadata, test_metadata)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wpttest.py", line 628, in from_manifest
    return test_cls.from_manifest(manifest_file, manifest_test, inherit_metadata, test_metadata)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wpttest.py", line 492, in from_manifest
    quic=quic)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wpttest.py", line 465, in __init__
    self.viewport_size = self.get_viewport_size(viewport_size)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wpttest.py", line 559, in get_viewport_size
    assert override is None

[jdm]

This is triggered by our existing tests like https://github.com/servo/servo/blob/master/tests/wpt/mozilla/tests/css/pixel_snapping_border_a.html#L7 which have a viewport-size override.

[jdm]

This will be fixed by a combination of #26772 and web-platform-tests/wpt#23956.

[jdm]

Latest bustage before the previous fix could be verified:

Error running mach:
    ['test-wpt', '--release', '--processes', '20', '--log-raw', 'test-wpt-py3.log', '--log-errorsummary', 'wpt-py3-errorsummary.log', 'url']
The error occurred in code that was called by the mach command. This is either
a bug in the called code itself or in the way that mach is calling it.
You can invoke |./mach busted| to check if this issue is already on file. If it
isn't, please use |./mach busted file| to report it. If |./mach busted| is
misbehaving, you can also inspect the dependencies of bug 1543241.
If filing a bug, please include the full output of mach, including this error
message.
The details of the failure are as follows:
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 45840: ordinal not in range(128)
  File "/repo/python/servo/testing_commands.py", line 400, in test_wpt
    ret = self.run_test_list_or_dispatch(kwargs["test_list"], "wpt", self._test_wpt, **kwargs)
  File "/repo/python/servo/testing_commands.py", line 440, in run_test_list_or_dispatch
    return correct_function(**kwargs)
  File "/repo/python/servo/testing_commands.py", line 426, in _test_wpt
    return self.wptrunner(run_file, **kwargs)
  File "/repo/python/servo/testing_commands.py", line 478, in wptrunner
    return run_globals["run_tests"](**kwargs)
  File "/repo/tests/wpt/run.py", line 52, in run_tests
    success = wptrunner.run_tests(**kwargs)
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/wptrunner.py", line 216, in run_tests
    kwargs["enable_quic"]) as test_environment:
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/environment.py", line 97, in __enter__
    self.get_routes())
  File "/repo/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/environment.py", line 201, in get_routes
    headers=headers)
  File "/repo/tests/wpt/web-platform-tests/tools/serve/serve.py", line 354, in add_static
    handler = handlers.StaticHandler(path, format_args, content_type, **headers)
  File "/repo/tests/wpt/web-platform-tests/tools/wptserve/wptserve/handlers.py", line 470, in __init__
    data = f.read()
  File "/usr/lib/python3.6/encodings/ascii.py", line 26, in decode
    return codecs.ascii_decode(input, self.errors)[0]

[jdm]

I can reproduce this in a VM by running the following python script:

import sys
with open(sys.argv[1]) as f:
	f.read()

And running it with LANG=C python3 a.py tests/wpt/web-platform-tests/tools/third_party/pdf_js/pdf.js

[jdm]

Fixed by 604b565.