Patch by Michele Orrù.

Do we need a fallback implementation of getcwd() from 1991 that claims to
support "really old Unix systems"? I don't think so.

Patch by Stefan Behnel.

#18796: improve documentation of the file argument of dis.show_code.  Initial patch by Vajrasky Kok.

caches.

Eliminates the ResoureWarning raised during testing.

Patch also independently written by Vajrasky Kok.

context when raising a new KeyError with the original key.

when raising a new KeyError with the original key.

multiple times.

With importlib getting used more and more, changing __import__ will
not work as well as people used to hope as it will potentially bypass
importers, etc. It also will not work with importlib.import_module()
as it uses "importlib.__import__" (i.e. importlib's implementation of
import) directly and not builtins.__import__.

(grafted from 1ea833ecaf5a9d43a886e9e73b4e2551d0d5b548)

It suffices to keep just one reference when the object is created.

argument.

This is needed for support Tcl/Tk 8.6.

argument.

This is needed for support Tcl/Tk 8.6.

fork() is suppose to be async-signal safe but the handler calls unsafe functions. A parent handler mitigates the issue.

fork() is suppose to be async-signal safe but the handler calls unsafe functions. A parent handler mitigates the issue.