Save created server as global when running test/dev servers

Useful for playing with ssl configurations and generally for being
able to inspect server state in development and testing.

This only makes sense when running the server in a thread, of course.

src/ZEO/tests/forker.py

@@ -108,6 +108,7 @@ def runner(config, qin, qout, timeout=None,
         options = ZEO.runzeo.ZEOOptions()
         options.realize(['-C', config])
         server = ZEO.runzeo.ZEOServer(options)
+        globals()[(name if name else 'last') + '_server'] = server
         server.open_storages()
         server.clear_socket()
         server.create_server()