CORD-1846: First argument to structlog logging functions must be a
string

Change-Id: Iffa0def4e513c173cdcb6f2e605870e323cbce3b
diff --git a/grpc_client/grpc_client.py b/grpc_client/grpc_client.py
index 9dee5db..62814ef 100644
--- a/grpc_client/grpc_client.py
+++ b/grpc_client/grpc_client.py
@@ -122,7 +122,7 @@
             if e.code() == grpc.StatusCode.UNAVAILABLE:
                 log.info('grpc-endpoint-not-available')
             else:
-                log.exception(e)
+                log.exception('rendezvous error', e=e)
             yield self._backoff('not-available')
 
         except Exception, e: