Issue #19421: fix a check in warnings.warn() to be able to use it during Python
finalization.

sys.argv is set to None during Python finalization: add PyList_Check() to avoid
a crash in PyList_Size().
Issue #19421: add an unit test for warnings.warn() during finalization
#19395: Raise exception when pickling a (BZ2|LZMA)(Compressor|Decompressor).

The underlying C libraries provide no mechanism for serializing compressor and
decompressor objects, so actually pickling these classes is impractical.
Previously, these objects would be pickled without error, but attempting to use
a deserialized instance would segfault the interpreter.
#19395: Raise exception when pickling a (BZ2|LZMA)(Compressor|Decompressor).

The underlying C libraries provide no mechanism for serializing compressor and
decompressor objects, so actually pickling these classes is impractical.
Previously, these objects would be pickled without error, but attempting to use
a deserialized instance would segfault the interpreter.
Merge.
Issue #18509: handle PyUnicode_Writer() error
CJK codecs: remove unused TRYMAP_ENC_MPLANE macro
CJK codecs: use less magic and more readable macros, write explicit if
CJK codecs: add newlines for readability
Issue #19425 -- a pickling error should not cause pool to hang.
CJK codecs: less magic macros, require explicit semicolon
CJK codecs: less magical macros, semicolon is now explicit
Issue #18408: Add a new PyFrame_FastToLocalsWithError() function to handle
exceptions when merging fast locals into f_locals of a frame.
PyEval_GetLocals() now raises an exception and return NULL on failure.
Issue #18408: Fix PyUnicode_AsUTF8AndSize(), raise MemoryError exception on
memory allocation failure
Issue #19428: zipimport now handles errors when reading truncated or invalid
ZIP archive.
Issue #18408: Fix zipimport, handle PyUnicode_Substring() and get_subname() failures
Issue #18408: Fix iobase_readline(), handle PyByteArray_Resize() failure
Issue #18408: Fix error handling in PyBytes_FromObject()

_PyBytes_Resize(&new) sets new to NULL on error, don't call Py_DECREF() with NULL.
Issue #18408: Fix bytearrayiter.partition()/rpartition(), handle
PyByteArray_FromStringAndSize() failure (ex: on memory allocation failure)
Issue #18408: Fix _ctypes_alloc_format_string(), raise MemoryError on memory
allocation failure