Version 2.8.1 (2019-11-03)

Data updates

• Updated tzdata version to 2019c.

Bugfixes

• Fixed a race condition in the tzoffset and tzstr \"strong\" caches on Python 2.7. Reported by \@kainjow (gh issue #901).
• Parsing errors will now raise ParserError, a subclass of ValueError, which has a nicer string representation. Patch by \@gfyoung (gh pr #881).
• parser.parse will now raise TypeError when tzinfos is passed a type that cannot be interpreted as a time zone. Prior to this change, it would raise an UnboundLocalError instead. Patch by \@jbrockmendel (gh pr #891).
• Changed error message raised when when passing a bytes object as the time zone name to gettz in Python 3. Reported and fixed by \@labrys () (gh issue #927, gh pr #935).
• Changed compatibility logic to support a potential Python 4.0 release. Patch by Hugo van Kemenade (gh pr #950).
• Updated many modules to use tz.UTC in favor of tz.tzutc() internally, to avoid an unnecessary function call. (gh pr #910).
• Fixed issue where dateutil.tz was using a backported version of contextlib.nullcontext even in Python 3.7 due to a malformed import statement. (gh pr #963).

Tests

• Switched from using assertWarns to using pytest.warns in the test suite. (gh pr #969).
• Fix typo in setup.cfg causing PendingDeprecationWarning to not be explicitly specified as an error in the warnings filter. (gh pr #966)
• Fixed issue where test_tzlocal_offset_equal would fail in certain environments (such as FreeBSD) due to an invalid assumption about what time zone names are provided. Reported and fixed by Kubilay Kocak (gh issue #918, pr #928).
• Fixed a minor bug in test_isoparser related to bytes/str handling. Fixed by \@fhuang5 (gh issue #776, gh pr #879).
• Explicitly listed all markers used in the pytest configuration. (gh pr #915)
• Extensive improvements to the parser test suite, including the adoption of pytest-style tests and the addition of parametrization of several test cases. Patches by \@jbrockmendel (gh prs #735, #890, #892, #894).
• Added tests for tzinfos input types. Patch by \@jbrockmendel (gh pr #891).
• Fixed failure of test suite when changing the TZ variable is forbidden. Patch by \@shadchin (gh pr #893).
• Pinned all test dependencies on Python 3.3. (gh prs #934, #962)

Documentation changes

• Fixed many misspellings, typos and styling errors in the comments and documentation. Patch by Hugo van Kemenade (gh pr #952).

Misc

• Added Python 3.8 to the trove classifiers. (gh pr #970)
• Moved as many keys from setup.py to setup.cfg as possible. Fixed by \@FakeNameSE, \@aquinlan82, \@jachen20, and \@gurgenz221 (gh issue #871, gh pr #880).
• Reorganized parser methods by functionality. Patch by \@jbrockmendel (gh pr #882).
• Switched release.py over to using pep517.build for creating releases, rather than direct invocations of setup.py. Fixed by \@smeng10 (gh issue #869, gh pr #875).
• Added a \"build\" environment into the tox configuration, to handle dependency management when making releases. Fixed by \@smeng10 (gh issue #870,r gh pr #876).
• GH #916, GH #971