Issue #19936: Disable shebang lines in order to prevent using a random
system python.
Merge from 3.3.
update pysqlite website (closes #20278)
merge 3.3 (#20278)
linkify chain.from_iterable (closes #20272)
merge 3.3 (#20272)
Issue #19936: Added executable bits or shebang lines to Python scripts which
requires them.  Disable executable bits and shebang lines in test and
benchmark files in order to prevent using a random system python, and in
source files of modules which don't provide command line interface.  Fixed
shebang line to use python3 executable in the unittestgui script.
Merge heads
Issue #19936: Added executable bits or shebang lines to Python scripts which
requires them.  Disable executable bits and shebang lines in test and
benchmark files in order to prevent using a random system python, and in
source files of modules which don't provide command line interface.  Fixed
shebang lines in the unittestgui and checkpip scripts.
Issue #19936: Remove executable bits from C source files and several forgotten
test files.
Issue #19936: Remove executable bits from C source files and several forgotten
test files.
asyncio: add a new "Develop with asyncio" section to the documentation
asyncio doc: replace "coroutine" with "coroutine object" or "coroutine function"
asyncio: Reincarnate CoroWrapper's docstring as a comment.
Issue #20226: Major improvements to Argument Clinic.

* You may now specify an expression as the default value for a
  parameter!  Example: "sys.maxsize - 1".  This support is
  intentionally quite limited; you may only use values that
  can be represented as static C values.
* Removed "doc_default", simplified support for "c_default"
  and "py_default".  (I'm not sure we still even need
  "py_default", but I'm leaving it in for now in case a
  use presents itself.)
* Parameter lines support a trailing '\\' as a line
  continuation character, allowing you to break up long lines.
* The argument parsing code generated when supporting optional
  groups now uses PyTuple_GET_SIZE instead of PyTuple_GetSize,
  leading to a 850% speedup in parsing.  (Just kidding, this
  is an unmeasurable difference.)
* A bugfix for the recent regression where the generated
  prototype from pydoc for builtins would be littered with
  unreadable "=<object ...>"" default values for parameters
  that had no default value.
* Converted some asserts into proper failure messages.
* Many doc improvements and fixes.
Issue #20226: Added tests for new features and regressions.