2.6.3
Add a setting to customize the asyncio event loop (#4414)
Typing: switch to a newer version of MyPy to check types
Specify Twisted reactor (TWISTED_REACTOR setting) (#4294)
Set WindowsSelectorEventLoopPolicy on Windows (#5315)
CachingHostnameResolver tests
CrawlerProcess: test a multi-spider scenario
If TWISTED_REACTOR is None, reuse any pre-installed reactor (#5528)
Add a test for a CrawlerProcess script. (#4218)
Add tests for TWISTED_REACTOR in custom_settings.
Fix a reactor test on Windows.