As per David's review.

Padding circuits were regular cells that got closed before their padding
machine could finish. This means that they can still receive regular cells from
their past life, but they have no way or reason to answer them anymore. Hence
let's ignore them before they even get to the proper subsystems.

One function does the validation, the other does the handling.

Padding circuits were regular cells that got closed before their padding
machine could finish. This means that they can still receive regular cells from
their past life, but they have no way or reason to answer them anymore. Hence
let's ignore them before they even get to the proper subsystems.

I had the logic reversed here.

Since we sometimes call practracker directly, that's where we should
check the TOR_DISABLE_PRACTRACKER envvar.

This test runs practracker with a set of 0 thresholds, to make sure
that it enumerates all its values right.  It tries running with an
empty exceptions file, and with an exceptions file that covers
_some_ of the data, and it makes sure that the outputs are as expected.

Now that there is only one toplevel place where we print problems,
we can redirect just that one print to a file when we are
regenerating the exceptions.txt file.  Previously we redirected
sys.stdout, which is naughty, and forced us to send warnings (and
warnings alone) to stderr.

These flags let you suppress the message about the number of
problems and warnings, and let you control the thresholds above
which something counts as a problem.

I need this for testing.

Previously warnings were generated by magic inside ProblemVault; now
they're printed on demand.

Instead of having "consider" functions that have to call a global
ProblemVault, we can now generate all the metrics for the code
separately from the decision about what to do for them.

I'm about to refactor the code into a set of iterators that yield
*all* the metrics for the code, and then add a filter on top of that
to return the problems.

"ours" to avoid version bump.

Signed-off-by: David Goulet <dgoulet@torproject.org>

"ours" to avoid version bump.