This is a nasty work around for: https://bugs.python.org/issue27456

It can't always be applied.  For example, it can't be applied to Linux
SSL sockets using the asyncio-provided loop.

It's a shame that Tox is unable (or unwilling) to get test
dependencies from package meta data. :(

I develop on a mac (for better or worse) so I know that mac tests are being run.

- To make tests run faster with j99, and

- To isolate some tests that often seem to fail spuriously but pass
  when run by themselves.

And maybe avoid spurious test failures due to port contention.

It appeared that some tests were failing because servers weren't
closing down.  Modified the test forker module and the server to be
more paranoid about closing the server.

This seems to have helped test stability. (Or maybe I accidentally
fixed something while flailing :)).

Where we check for a disconnect, get disconnected and vote

Because running it single-threaded was unstable, at least in the tests.

See http://bugs.python.org/issue27392

SSL didn't work on Linux because of an incompatibility between
non-blocking sockerts and SSL (which wasn't an issue on Mac OS X for
some reason).

I decided to try switching the server to use a single thread.  This
led to a performance improvement for zodbshootout and a lower-level
networking test.  I refactored the server listening logic and kept (at
least for now) both the multi-threaded and the single-threaded
version. (The multi-threaded logic can be used by changing a single
import. Tests pass with both.).

I'm a bit worried about the asyncio server. See

  http://bugs.python.org/issue27386

Tests appear to be less stable using asyncio.server on my Mac. :(

So travis doesn't hate us.

Because we were computing the size info in the commit callback, which
might be before before the inderlying data were committed.  This caused the computation to be wrong in some cases.

Instead we get and send the size information after committing.

To allow test servers to shut down in a timely manner.

Also, some more debug logging.

Asyncio server

What it was testing is more sanely tested by the zeo-fan-out test.