The old code expected a dict with int keys, but iterables are simpler, so get
rid of a lot of dict.fromkeys() nonsense.

It didn't work because the os module is frozen on 3.11, so it gets no
measurement.  Use -X to disable the frozen modules feature for the test.

The fix for CTracer is egregious and will need to be updated when there's a
supported way to do it.

The fullcoverage skip is noted in
https://github.com/nedbat/coveragepy/issues/1278

The raise_through_with skip is noted in
https://github.com/nedbat/coveragepy/issues/1270

Originally I used setup_test because something went wrong when I used setUp.  I
wrote https://github.com/pytest-dev/pytest/issues/8424 about it.  There they say
to use `-p no:nose` to disable nose interpretation.

But now I simply went back to setUp, and all seems well? Not sure what changed,
but using the expected name is better.

Python 3.11 made a traceback look like this:

    Traceback (most recent call last):
      File "{path}", line 8, in <module>
        print(sys.argv[1])
              ~~~~~~~~^^^
    IndexError: list index out of range

We needed to not care if that tilde-caret line was present or not.

and also replace some calls with just-plain re.search.