This was achieved by:
* moving many pass statements in tests onto their own lines, so they pass line coverage and can match an easy ignore pattern if branch coverage is added later.
* removing code that cannot be reached.
* removing long-disabled tests.
* removing unused code.
* adding tests for uncovered code
It turned out that removing `if __name__ == '__main__'` blocks that run unittest.main() at the bottom of test files was surprisingly contentious, so they remain and can be filtered out with an appropriate .coveragerc.
* Resolve string target to patch.dict during function call
* Add NEWS entry
* Remove unneeded call
* Restore original value for support.target and refactor assertions
* Add extra assertion to verify unpatched dict
Chris Withers
Xtreak
Mario Corchero
Berker Peksag
Michael Foord