"raised" without setting x, err, or why to let the eval loop know.

string allocation.

It doesn't make sense for such a fundamental document to have
the most obscure function listed at the top.

Took Nick Coghlan's advice about importing warnings globally in logging, to avoid the possibility of race conditions: "This could deadlock if a thread spawned as a side effect of importing a module happens to trigger a warning. warnings is pulled into sys.modules as part of the interpreter startup - having a global 'import warnings' shouldn't have any real effect on logging's import time."

process on success or raise an exception on error.

support unusual filenames (such as those containing semi-colons) in
Content-Disposition headers.

Issue #4384: Added logging integration with warnings module using captureWarnings(). This change includes a NullHandler which does nothing; it will be of use to library developers who want to avoid the "No handlers could be found for logger XXX" message which can appear if the library user doesn't configure logging.