- Added wait-until parameter for begin_nbo_phase_two().

- Retry enter_toi() in poll_enter_toi() also for error_connection_failed
  which means that the connectivity to the cluster has been lost,
  a.k.a non-prim.

include/wsrep/provider.hpp

@@ -237,7 +237,8 @@ namespace wsrep
             error_size_exceeded,
             /** Connectivity to cluster lost */
             error_connection_failed,
-            /** Internal provider failure, provider must be reinitialized */
+            /** Internal provider failure or provider was closed,
+                provider must be reinitialized */
             error_provider_failed,
             /** Fatal error, server must abort */
             error_fatal,