* Add Lib/test/pythoninfo.py: script collecting various informations
  about Python to help debugging test failures.
* regrtest: remove sys.hash_info and sys.flags from header.
* Travis CI, Appveyor: run pythoninfo before tests

Tools/scripts/patchcheck.py now ignores changes in directories which
are copies of external libraries:

* Modules/_ctypes/libffi_msvc/
* Modules/_ctypes/libffi_osx/
* Modules/_decimal/libmpdec/
* Modules/expat/
* Modules/zlib/

Drop also support for Mercurial, since CPython migrated to Git.

Exclude also libmpdec

patchcheck: exclude also libffi_osx and libffi_msvc

Change the option for `Français` into `French` to be consistent with the other language selections that are already in English.

bpo-18966: non-daemonic threads created by a multiprocessing.Process should be joined on exit (#3111)

* bpo-18966: non-daemonic threads created by a multiprocessing.Process should be joined on exit

* Add NEWS blurb

Fix a warning about dangling processes in test_rapid_restart() of
_test_multiprocessing: join the process.

* Revert "Add Bruno Penteado to ACKS (#3091)"

This reverts commit f978405b.

* Revert "bpo-30983: eval frame rename in pep 0523 broke gdb's python extension (#2803)"

This reverts commit 2e0f4db1.

  The slightly modified tests continue to pass.  Patch by Cheryl Sabella.

OpenSSL 1.1.0 to 1.1.0e aborted the handshake when server and client
could not agree on a protocol using ALPN. OpenSSL 1.1.0f changed that.
The most recent version now behaves like OpenSSL 1.0.2 again. The ALPN
callback can pretend to not been set.

See https://github.com/openssl/openssl/pull/3158 for more details
Signed-off-by: Christian Heimes <christian@python.org>

Patch by Cheryl Sabella.

pep 0523 renames PyEval_EvalFrameEx to _PyEval_EvalFrameDefault while the gdb python extension only looks for PyEval_EvalFrameEx to understand if it is dealing with a frame.

Final effect is that attaching gdb to a python3.6 process doesnt resolve python objects. Eg. py-list and py-bt dont work properly.

This patch fixes that. Tested locally on python3.6

* Make error message more informative

Replace assertions in error-reporting code with more-informative version that doesn't cause confusion over where and what the error is.

* Additional clarification + get travis to check

* Change from SystemError to TypeError

As suggested in PR comment by @pitrou, changing from SystemError; TypeError appears appropriate.

* NEWS file installation; ACKS addition (will do my best to justify it by additional work)

_Py_atomic_* are currently not implemented as atomic operations
when building with MSVC. This patch attempts to implement parts
of the functionality required.

Remove unneeded word `to`.

_test_multiprocessing now marks the test as ENV_CHANGED on dangling
process or thread.

* reap_children() now sets environment_altered to True to detect bugs
  using python3 -m test --fail-env-changed
* Replace bare "except:" with "except OSError:" in reap_children()
* Write an unit test for reap_children() using a timeout of 60
  seconds

* Add socketserver.ForkingMixIn.server_close()

bpo-31151: socketserver.ForkingMixIn.server_close() now waits until
all child processes completed to prevent leaking zombie processes.

* Fix test on Windows which doesn't have ForkingMixIn

TestRandomNameSequence.test_process_awareness() now calls
os.waitpid() to avoid leaking a zombie process.

The current test_child_terminated_in_stopped_state() function test
creates a child process which calls ptrace(PTRACE_TRACEME, 0, 0) and
then crash (SIGSEGV). The problem is that calling os.waitpid() in the
parent process is not enough to close the process: the child process
remains alive and so the unit test leaks a child process in a
strange state. Closing the child process requires non-trivial code,
maybe platform specific.

Remove the functional test and replaces it with an unit test which
mocks os.waitpid() using a new _testcapi.W_STOPCODE() function to
test the WIFSTOPPED() path.

Idlelib.calltips.get_argspec now uses inspect.signature instead of inspect.getfullargspec, like help() does.  This improves the signature in the call tip in a few different cases, including builtins converted to provide a signature.  A message is added if the object is not callable, has an invalid signature, or if it has positional-only parameters.
Patch by Louie Lu.

TestModule.test_after_fork() now calls os.waitpid() to read the exit
status of the child process to avoid creating a zombie process.

Add a post_test_cleanup() function which currently only calls
support.reap_children().

PtyTests.run_child() now calls os.waitpid() to read the exit status
of the child process to avoid creating zombie process and leaking
processes in the background.

This fix a regex issue (a missing non-matching group around an 'or'
list) and the specific possible case where a translation is built but
not yet in known by the picker, but not explicitly listing possible
languages in the regex.

bpo-31072: Add a filter argument to zipapp.create_archive (GH-3021)

* Add an include_file argument to allow callers to decide which files to include
* Document the new argument

bpo-31135: Call the parent destroy() method even if the used
attribute doesn't exist.

The LabeledScale.destroy() method now also explicitly clears label
and scale attributes to help the garbage collector to destroy all
widgets.

Initial patch by Victor Stinner.