- Instead of making it optional, always set up a handler, but possibly
going to /dev/null. This simplifies the code by removing a lot of
conditionals. It also can replace the NullHandler() we already add.
- Change `set_log_path` to just change the stream, instead of recreating
one. Besides plugging a resource leak, it enables the next item.
- Remove the capturing_logs from _runtest_for, since it sufficiently
covered by the one in pytest_runtestloop now, which wraps all other
_runtest_for calls.
The first item alone would have had an adverse performance impact, but
the last item removes it.
075903dafa