* Py_Main() now starts by reading Py_xxx configuration variables to
  only work on its own private structure, and then later writes back
  the configuration into these variables.
* Replace Py_GETENV() with pymain_get_env_var() which ignores empty
  variables.
* Add _PyCoreConfig.dump_refs
* Add _PyCoreConfig.malloc_stats
* _PyObject_DebugMallocStats() is now responsible to check if debug
  hooks are installed. The function returns 1 if stats were written,
  or 0 if the hooks are disabled. Mark _PyMem_PymallocEnabled() as
  static.

Remove also the initstr variable, unused since the commit
e69f0df4 pushed in 2012: "bpo-13959:
Re-implement imp.find_module() in Lib/imp.py"

* Simplify _PyCoreConfig_INIT, _PyMainInterpreterConfig_INIT,
  _PyPathConfig_INIT macros: no need to set fields to 0/NULL, it's
  redundant (the C language sets them to 0/NULL for us).
* Fix typo: pymain_run_statup() => pymain_run_startup()
* Remove a few XXX/TODO

The undecodable file name cannot be created on macOS APFS file systems.

* Rather than raise TypeError, warn and call list() on the value.

* Fix tests, revise NEWS and whatsnew text.

* Revise documentation, a string is okay as well.

* Ensure 'requires' and 'obsoletes' are real lists.

* Test that requires and obsoletes are turned to lists.

When tk event handling is driven by IDLE's run loop, a confusing
and distracting queue.EMPTY traceback context is no longer added
to tk event exception tracebacks.  The traceback is now the same
as when event handling is driven by user code.  Patch based on
a suggestion by Serhiy Storchaka.

Patches are in 3.7.0a3 even if this update is not.

* Revert "bpo-32197: Try to fix a compiler error on OS X introduced in bpo-32030. (#4681)"

This reverts commit 13badcbc.

Re-apply commits:

* "bpo-32030: _PyPathConfig_Init() sets home and program_name (#4673)"
  commit af5a8950.
* "bpo-32030: Fix config_get_program_name() on macOS (#4669)"
  commit e23c06e2.
* "bpo-32030: Add Python/pathconfig.c (#4668)"
  commit 0ea395ae.
* "bpo-32030: Don't call _PyPathConfig_Fini() in Py_FinalizeEx() (#4667)"
  commit ebac19da.
* "bpo-32030: Fix Py_GetPath(): init program_name (#4665)"
  commit 9ac3d888.

* Fix compilation error on macOS

Also fixed searching patterns that could match an empty string.

uuid.get_node() always must return a stable result.
Also added a test for non-reproducibility of _random_getnode().
Original patch by Xavier de Gaye.

The original algorithm tried to delegate the folding to the tokens so
that those tokens whose folding rules differed could specify the
differences.  However, this resulted in a lot of duplicated code because
most of the rules were the same.

The new algorithm moves all folding logic into a set of functions
external to the token classes, but puts the information about which
tokens can be folded in which ways on the tokens...with the exception of
mime-parameters, which are a special case (which was not even
implemented in the old folder).

This algorithm can still probably be improved and hopefully simplified
somewhat.

Note that some of the test expectations are changed.  I believe the
changes are toward more desirable and consistent behavior: in general
when (re) folding a line the canonical version of the tokens is
generated, rather than preserving errors or extra whitespace.

instead of crashing due to a stack overflow.

This perhaps will fix similar problems in other extension types.

Add import_find_and_load() helper function.  The addition of
the importtime option has made PyImport_ImportModuleLevelObject() large
and so using a helper seems worthwhile.  It also makes it clearer that
abs_name is the only argument needed by _find_and_load().

Previously, CO_NOFREE was set in the compiler, which meant
it could end up being set incorrectly when code objects
were created directly. Setting it in the constructor based
on freevars and cellvars ensures it is always accurate,
regardless of how the code object is defined.

Also addresses doc build failures documented in bpo-32200.

If the marshal or bytecode formats get changed, frozen.c needs to
be updated as well.  It can be easy to miss this step and not doing
so can cause test_importlib to crash in mysterious ways.  Add an
explict unit test to make it easier to track down the problem.

* Revert "bpo-32030: _PyPathConfig_Init() sets home and program_name (#4673)"

This reverts commit af5a8950.

* Revert "bpo-32030: Fix config_get_program_name() on macOS (#4669)"

This reverts commit e23c06e2.

* Revert "bpo-32030: Add Python/pathconfig.c (#4668)"

This reverts commit 0ea395ae.

* Revert "bpo-32030: Don't call _PyPathConfig_Fini() in Py_FinalizeEx() (#4667)"

This reverts commit ebac19da.

* Revert "bpo-32030: Fix Py_GetPath(): init program_name (#4665)"

This reverts commit 9ac3d888.

_PyPathConfig_Init() now also initialize home and program_name:

* Rename existing _PyPathConfig_Init() to _PyPathConfig_Calculate().
  Add a new _PyPathConfig_Init() function in pathconfig.c which
  handles the _Py_path_config variable and call
  _PyPathConfig_Calculate().
* Add home and program_name fields to _PyPathConfig.home
* _PyPathConfig_Init() now initialize home and program_name
  from main_config
* Py_SetProgramName(), Py_SetPythonHome() and Py_GetPythonHome() now
  calls Py_FatalError() on failure, instead of silently ignoring
  failures.
* config_init_home() now gets directly _Py_path_config.home to only
  get the value set by Py_SetPythonHome(), or NULL if
  Py_SetPythonHome() was not called.
* config_get_program_name() now gets directly
  _Py_path_config.program_name to only get the value set by
  Py_SetProgramName(), or NULL if Py_SetProgramName() was not called.
* pymain_init_python() doesn't call Py_SetProgramName() anymore,
  _PyPathConfig_Init() now always sets the program name
* Call _PyMainInterpreterConfig_Read() in
  pymain_parse_cmdline_envvars_impl() to control the memory allocator
* C API documentation: it's no more safe to call Py_GetProgramName()
  before Py_Initialize().

* Factorize code from PC/getpathp.c and Modules/getpath.c to remove
  duplicated code
* rename pathconfig_clear() to _PyPathConfig_Clear()
* Inline _PyPathConfig_Fini() in pymain_impl() and then remove it,
  since it's a oneliner

Changes:

* _PyPathConfig_Fini() cannot be called in Py_FinalizeEx().
  Py_Initialize() and Py_Finalize() can be called multiple times, but
  it must not "forget" parameters set by Py_SetProgramName(),
  Py_SetPath() or Py_SetPythonHome(), whereas _PyPathConfig_Fini()
  clear all these parameters.
* config_get_program_name() and calculate_program_full_path() now
  also decode paths using Py_DecodeLocale() to use the
  surrogateescape error handler, rather than decoding using
  mbstowcs() which is strict.
* Change _Py_CheckPython3() prototype: () => (void)
* Truncate a few lines which were too long

* _PyMainInterpreterConfig_ReadEnv() now sets program_name from
  environment variables and pymain_parse_envvars() implements the
  falls back on argv[0].
* Remove _PyMain.program_name: use the program_name from
  _PyMainInterpreterConfig
* Move the Py_SetProgramName() call back to pymain_init_python(),
  just before _Py_InitializeCore().
* pathconfig_global_init() now also calls
  _PyMainInterpreterConfig_Read() to set program_name if it isn't set
  yet
* Cleanup PyCalculatePath: pass main_config to subfunctions to get
  directly fields from main_config (home, module_search_path_env and
  program_name)

* Rename PyPathConfig structure to _PyPathConfig and move it to
  Include/internal/pystate.h
* Rename path_config to _Py_path_config
* _PyPathConfig: Rename program_name field to program_full_path
* Add assert(str != NULL); to _PyMem_RawWcsdup(), _PyMem_RawStrdup()
  and _PyMem_Strdup().
* Rename calculate_path() to pathconfig_global_init(). The function
  now does nothing if it's already initiallized.