Issue #26588: Fix _tracemalloc start/stop: don't play with the reentrant flag.

set_reentrant(1) fails with an assertion error if tracemalloc_init() is called
first in a thread A and tracemalloc_start() is called second in a thread B. The
tracemalloc is imported in a thread A. Importing the module calls
tracemalloc_init(). tracemalloc.start() is called in a thread B.

uuid.uuid4() always uses os.urandom() after 756d040aa8e8.

Patch by jgauthier.

Patch by Andrew Szeto.

Without the patch, line 1010 of Lib/datetime.py wasn't covered
by the test suite.

Patch by Colin Williams.

Initial patch by Peter Inglesby.

#26250: document the sqlite3.Cursor.connection attribute.  Initial patches by Aviv Palivoda and Varpu Rantala.

configure script related to compiler flags.

Thanks to Daniel Shaulov for the bug report and patch.

Patch by SilentGhost.

files cannot be written.

Issue #26569: Fix pyclbr.readmodule() and pyclbr.readmodule_ex() to support
importing packages.

Issue #26563: Py_FatalError: disable faulthandler before trying to flush
sys.stdout and sys.stderr.

Issue #26563: Replace PyMem_Malloc() with PyMem_RawFree() since
PostToQueueCallback() calls PyMem_RawFree() (previously PyMem_Free()) in a new
C thread which doesn't hold the GIL.

Issue #26564. Cleanup the code, lineno is never negative.

Issue #26558.

Issue #26558: If Py_FatalError() is called without the GIL, don't try to print
the current exception, nor try to flush stdout and stderr: only dump the
traceback of Python threads.

Patch from Victor van den Elzen.

Ignore pip warning in test_venv.test_with_venv().

Issue #17758: Skip test_site if site.USER_SITE directory doesn't exist and
cannot be created.

#25687: clarify that errors in tearDown increase the total number of reported errors.  Initial patch by HyeSoo Park.