Issue #19551: Update installer Welcome file.
Issue #8813: X509_VERIFY_PARAM is only available on OpenSSL 0.9.8+
The patch removes the verify_flags feature on Mac OS X 10.4 with OpenSSL 0.9.7l 28 Sep 2006.
Fix transport docstrings
Issue #15663: Revert OS X installer built-in Tcl/Tk support for 3.4.0b1.
merge
Issue #18874: Implement the PEP 454 (tracemalloc)
Issue #18874: Remove tracemalloc.set_traceback_limit()

tracemalloc.start() now has an option nframe parameter
Document asyncio transport APIs
Start documenting the event loop