Travis CI: Find and fix Python syntax errors

Here's a PR from a new contributor: https://github.com/torproject/tor/pull/1686

changed milestone to %Tor: 0.4.4.x-final

Trac:
Child Ticket(s): #33192 (moved), #33196 (moved), #33203 (moved), #33204 (moved), #32791 (moved)

added component::core tor/tor extra-review milestone::Tor: 0.4.4.x-final priority::medium severity::normal status::needs-revision type::enhancement labels

I'm still working on revisions with the author of the PR.

But I have a question for Nick: Does this change belong in 0.4.3 or 0.4.4?

I think catching python syntax errors is a good idea.

And this change could enforce python 3 compatibility in all our scripts, if we change the python version to a recent python 3. (But I think we should do that in a separate ticket, in case there are any errors we need to fix.)

Trac:
Status: new to needs_revision

I think 0.4.4 might be a better idea, and here's why: new code-checking tooling often comes with significant false positives or similar issues to work around, and often takes a few rounds of revision till it works right everywhere.

With that in mind, I think we should aim to do this in 0.4.4, and only do things in 0.4.3 that stabilize it. But I could probably be persuaded elsewise if I'm missing something here.

I think 0.4.4 is a good release to target. This is an active area right now, and there are a bunch of new volunteers, so let's do it right.

That said, if we could open the merge window for 0.4.4 soon, then it would help these volunteers collaborate from master (rather than working off each other's branches).

Trac:
Summary: Travis CI: Use flake8 to find Python syntax errors to Travis CI: Find and fix Python syntax errors
Milestone: Tor: 0.4.3.x-final to Tor: 0.4.4.x-final

mentioned in issue #33194 (moved)

mentioned in issue #33196 (moved)

mentioned in issue #32791 (moved)

mentioned in issue #33192 (moved)

mentioned in issue #33204 (moved)

mentioned in issue #33203 (moved)

moved to tpo/core/tor#33193 (closed)

mentioned in issue tpo/core/tor#33196 (closed)