revert #100, use latest eventlet

ryu/controller/controller.py

@@ -30,7 +30,6 @@ from socket import TCP_NODELAY
 from socket import SHUT_WR
 from socket import timeout as SocketTimeout
 import ssl
-import sys
 
 from ryu import cfg
 from ryu.lib import hub
@@ -171,12 +170,6 @@ class OpenFlowController(object):
                 # anything less than python 2.7.9 supports only TLSv1
                 # or less, thus we choose TLSv1
                 ssl_args = {'ssl_version': ssl.PROTOCOL_TLSv1}
-            elif sys.version_info >= (3, 7,):
-                # On Python3.7+ we can't wrap an SSLContext due to this bug:
-                # https://github.com/eventlet/eventlet/issues/526
-                # Lets assume the system has a new enough OpenSSL that
-                # SSL is fully disabled.
-                ssl_args = {'ssl_version': ssl.PROTOCOL_TLSv1}
             else:
                 # from 2.7.9 and versions 3.4+ ssl context creation is
                 # supported. Protocol_TLS from 2.7.13 and from 3.5.3

tools/pip-requires

@@ -1,7 +1,7 @@
 # NOTE: OpenStack avoids some versions of eventlet, because of the
 # following issue.
 # https://github.com/eventlet/eventlet/issues/401
-eventlet!=0.18.3,>=0.18.2,!=0.20.1,!=0.21.0,!=0.23.0
+eventlet==0.30.0
 msgpack>=0.3.0,<1.0.0  # RPC library, BGP speaker(net_cntl)
 netaddr
 oslo.config>=2.5.0