mmap obmalloc arenas so that they may be immediately returned to the system when unused (closes #20494)
Issue #20509: Added cross-reference in documentation.
Issue #20498: Fixed io.StringIO tests for newline='\n'. Added new tests.
Issue #19920: Added tests for TarFile.list(). Based on patch by Vajrasky Kok.
Issue #20374: Avoid compiler warnings when compiling readline with libedit.
Issue #20374: delete spurious empty line
Issue #20520: Fixed readline test in test_codecs.
Issue #20532: Tests which use _testcapi now are marked as CPython only.