Closes #13326.

Patch by Daniel Urban.

The find utility of OpenBSD doesn't support the "-exec cmd {} +"
action. Change it to use "-depth -exec cmd {} ;" instead.

Also, remove __pycache__ before *.py[co], as most bytecode files are
in __pycache__ directories. Only those generated by Python 2 under
Doc/tools are not.

Closes #13326.

to poll(2): don't set them.

Closes #13254.

Closes #13254.

variable in the default value of a keyword-only argument:
(lambda *, arg=GLOBAL_NAME: None)

variable in the default value of a keyword-only argument:
(lambda *, arg=GLOBAL_NAME: None)

_PyUnicode_CheckConsistency() checks also hash and length value for not ready
Unicode strings.

Thanks to Robert Xiao.