Clarify setting socket_options

There was a lot of code that would have no effect if kwargs already
had socket_options set. To make the code clearer, only execute the
code if it's going to have an effect.

Change-Id: Ic42f5a0bac07113aff59d36d19293dc6d65cd58a

keystoneclient/session.py

@@ -906,6 +906,7 @@ class TCPKeepAliveAdapter(requests.adapters.HTTPAdapter):
     http://blogs.msdn.com/b/windowsazurestorage/archive/2010/06/25/nagle-s-algorithm-is-not-friendly-towards-small-requests.aspx
     """
     def init_poolmanager(self, *args, **kwargs):
+        if 'socket_options' not in kwargs:
             socket_options = [
                 # Keep Nagle's algorithm off
                 (socket.IPPROTO_TCP, socket.TCP_NODELAY, 1),
@@ -929,5 +930,6 @@ class TCPKeepAliveAdapter(requests.adapters.HTTPAdapter):
             # seconds 4 times, these options should ensure that a connection
             # hands for no longer than 2 minutes before a ConnectionError is
             # raised.
-        kwargs.setdefault('socket_options', socket_options)
+
+            kwargs['socket_options'] = socket_options
         super(TCPKeepAliveAdapter, self).init_poolmanager(*args, **kwargs)