Python 3.7: all versions and old releases

Security
- bpo-41304: Fixes python3x._pth being ignored on Windows, caused by the fix for bpo-29778 (CVE-2020-15801).
- bpo-29778: Ensure python3.dll is loaded from correct locations when Python is embedded (CVE-2020-15523).
- bpo-41004: CVE-2020-14422: The __hash__() methods of ipaddress.IPv4Interface and ipaddress.IPv6Interface incorrectly generated constant hash values of 32 and 128 respectively. This resulted in always causing hash collisions. The fix uses hash() to generate hash values for the tuple of (address, mask length, network address).
- bpo-39603: Prevent http header injection by rejecting control characters in http.client.putrequest(…).
Core and Builtins
- bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() correctly
Library
- bpo-41288: Unpickling invalid NEWOBJ_EX opcode with the C implementation raises now UnpicklingError instead of crashing.
- bpo-39017: Avoid infinite loop when reading specially crafted TAR files using the tarfile module (CVE-2019-20907).
- bpo-41235: Fix the error handling in ssl.SSLContext.load_dh_params().
macOS
- bpo-41100: Additional fixes for testing on macOS 11 Big Sur Intel. Note: macOS 11 is not yet released, this release of Python is not fully supported on 11.0, and not all tests pass.

Tests
- bpo-41009: Fix use of support.require_{linux|mac|freebsd}_version() decorators as class decorator.
macOS
- bpo-41100: Fix configure error when building on macOS 11. Note that 3.7.8 was released shortly after the first developer preview of macOS 11 (Big Sur); there are other known issues with building and running on the developer preview. Big Sur is expected to be fully supported in a future bugfix release of Python 3.8.x and with 3.9.0.

Library
- bpo-13487: Avoid a possible “RuntimeError: dictionary changed size during iteration” from inspect.getmodule() when it tried to loop through sys.modules.
Documentation
- bpo-17422: The language reference no longer restricts default class namespaces to dicts only.

macOS
- bpo-38295: Prevent failure of test_relative_path in test_py_compile on macOS Catalina.

Library
- bpo-38368: Prevent ctypes crash when handling arrays in structs/unions.
- bpo-38449: Revert GH-15522, which introduces a regression in mimetypes.guess_type() due to improper handling of filenames as urls.
Windows
- bpo-38344: Fix syntax in activate.bat.

Core and Builtins
- bpo-37500: Due to unintended side effects, revert the change introduced by bpo-1875 in 3.7.4rc1 to check for syntax errors in dead conditional code blocks.
Documentation
- bpo-37149: Replace the dead link to the Tkinter 8.5 reference by John Shipman, New Mexico Tech, with a link to the archive.org copy.

There were no new changes in version 3.7.3.

Library
- bpo-31715: Associate .mjs file extension with application/javascript MIME Type.
Build
- bpo-35499: make profile-opt no longer replaces CFLAGS_NODIST with CFLAGS. It now adds profile-guided optimization (PGO) flags to CFLAGS_NODIST: existing CFLAGS_NODIST flags are kept.
- bpo-35257: Avoid leaking the linker flags from Link Time Optimizations (LTO) into distutils when compiling C extensions.
C API
- bpo-35259: Conditionally declare Py_FinalizeEx() (new in 3.6) based on Py_LIMITED_API. Patch by Arthur Neufeld.

Library
- bpo-34970: Protect tasks weak set manipulation in asyncio.all_tasks()

Library
- bpo-33851: Fix ast.get_docstring() for a node that lacks a docstring.
C API
- bpo-33932: Calling Py_Initialize() twice does nothing, instead of failing with a fatal error: restore the Python 3.6 behaviour.