Added a timeout argument to the ZEO4 server (copy)

It turns out the ZEO4 server doesn't shutdown cleanly in tests without
a shorter timeout (like the one I added for ZEO5).

For now, this is just in the copy used in the ZEO5 tests.  If I have
to updatre the copy at some point (hopefully not), then I'll add this
to ZEO4 proper.

src/ZEO/tests/ZEO4/StorageServer.py

@@ -1153,9 +1153,9 @@ def get_invalidations(self, storage_id, tid):
 
         return latest_tid, list(oids)
 
-    def loop(self):
+    def loop(self, timeout=30):
         try:
-            asyncore.loop(map=self.socket_map)
+            asyncore.loop(timeout, map=self.socket_map)
         except Exception:
             if not self.__closed:
                 raise # Unexpected exc

src/ZEO/tests/forker.py

@@ -134,8 +134,7 @@ def runner(config, qin, qout, timeout=None,
             qout.put(server.server.acceptor.addr)
         logger.debug('ADDRESS SENT')
         thread = threading.Thread(
-            target=server.server.loop,
-            kwargs={} if ZEO4_SERVER else dict(timeout=.2),
+            target=server.server.loop, kwargs=dict(timeout=.2),
             name = None if name is None else name + '-server',
             )
         thread.setDaemon(True)