Patch by Christoph Gohlke.
Closes #7639.

Issue #9343: Document that argparse parent parsers must be configured before their children. (Merge from 3.2.)

(so that stale test files, which can be very large, get wiped out)

Patch by Ben Hayden.

concurrent.futures.

concurrent.futures.

whole HTTP exchange, not only the opening.

for the names of optional and positional arguments in help messages.