Work better in server env with no keyrings

We should not try loading keyrings if we dont' have to. We
certainly should not print messages if keyrings are not even
needed

Fix for LP# 1145071

Change-Id: I700a2b40620359f6f1fbe03c6a6239d162ddea61

keystoneclient/client.py

@@ -33,17 +33,17 @@ from keystoneclient import exceptions
 _logger = logging.getLogger(__name__)
 
 
-# keyring init
-keyring_available = True
-try:
-    import keyring
-    import pickle
-except ImportError:
-    if (hasattr(sys.stderr, 'isatty') and sys.stderr.isatty()):
-        print >> sys.stderr, 'Failed to load keyring modules.'
-    else:
-        _logger.warning('Failed to load keyring modules.')
-    keyring_available = False
+def try_import_keyring():
+    try:
+        import keyring
+        import pickle
+        return True
+    except ImportError:
+        if (hasattr(sys.stderr, 'isatty') and sys.stderr.isatty()):
+            print >> sys.stderr, 'Failed to load keyring modules.'
+        else:
+            _logger.warning('Failed to load keyring modules.')
+        return False
 
 
 class HTTPClient(object):
@@ -121,7 +121,7 @@ class HTTPClient(object):
                 requests.logging.getLogger(requests.__name__).addHandler(ch)
 
         # keyring setup
-        self.use_keyring = use_keyring and keyring_available
+        self.use_keyring = use_keyring and try_import_keyring()
         self.force_new_token = force_new_token
         self.stale_duration = stale_duration or access.STALE_TOKEN_DURATION
         self.stale_duration = int(self.stale_duration)