Don't leak RPC connections on timeouts or other exceptions

Fixes bug 968843

Change-Id: I9e0f1e306cab203bf4c865050b7a45f96127062e

nova/rpc/amqp.py

@@ -38,6 +38,7 @@ from nova import flags
 from nova import log as logging
 from nova.openstack.common import local
 import nova.rpc.common as rpc_common
+from nova import utils
 
 LOG = logging.getLogger(__name__)
 
@@ -293,7 +294,11 @@ class MulticallWaiter(object):
         if self._done:
             raise StopIteration
         while True:
-            self._iterator.next()
+            try:
+                self._iterator.next()
+            except Exception:
+                with utils.save_and_reraise_exception():
+                    self.done()
             if self._got_ending:
                 self.done()
                 raise StopIteration