green.socket: create_connection: UnboundLocalError on Python3

Fixes https://github.com/eventlet/eventlet/issues/123

eventlet/green/socket.py

@@ -53,7 +53,8 @@ def create_connection(address,
             sock.connect(sa)
             return sock
 
-        except error as msg:
+        except error as e:
+            msg = e
             if sock is not None:
                 sock.close()
 

tests/socket_test.py

@@ -0,0 +1,8 @@
+from eventlet.green import socket
+
+
+def test_create_connection_error():
+    try:
+        socket.create_connection(('192.0.2.1', 80), timeout=0.1)
+    except (IOError, OSError):
+        pass