chance of sporadic failures.

This allows different parts of a program to use different methods for
starting processes without interfering with each other.

want to check that Connection.poll() doesn't crash.

Issue #18792: Use "127.0.0.1" or "::1" instead of "localhost" as much as possible, since "localhost" goes through a DNS lookup under recent Windows versions.

Also modify test code to hopefully avoid deadlock on failure.

See http://hg.python.org/sandbox/sbt#spawn

Zachary Ware.)

traceback raised when pool task raises an exception.

registry does not grow exponentially with generation of process.

  using the same sys.flags as the current process.
Backport from default branch.

fix for previous commit related to issue 10527 which didn't have the intended effect as per http://bugs.python.org/issue10527#msg179895

fix for previous commit related to issue 10527 which didn't have the intended effect as per http://bugs.python.org/issue10527#msg179895

connections on Windows.

Patch by Janne Karila.

Each manager test class now uses a separate manager.  Also, process
pools are no longer created before starting any tests.

Note that warnings are written if the manager for a test case still
has live objects when it is shutdown.  This is true for a few test cases
which fail to wait for all child processes to end.