greentest: add xtest__issue91.py

greentest/xtest__issue91.py

+from gevent.select import select
+from gevent.server import StreamServer
+from gevent import socket
+
+
+def handler(socket, address):
+    while True:
+        if not socket.recv(1000):
+            break
+
+
+server = StreamServer(('127.0.0.1', 0), handler)
+server.start()
+
+s = socket.create_connection(('127.0.0.1', server.server_port))
+while True:
+    select([], [s.fileno()] * 10, [])