Don't reset the convertor's position if it wasn't initialized before. This can

only happens for zero byte persistent requests.

This commit was SVN r10298.

ompi/mca/pml/ob1/pml_ob1_sendreq.h

@@ -297,7 +297,8 @@ do {
         if( sendreq->req_send.req_base.req_free_called ) {                              \
             MCA_PML_OB1_SEND_REQUEST_RETURN( sendreq );                                 \
         } else {                                                                        \
-            if(sendreq->req_send.req_base.req_ompi.req_persistent) {                    \
+            if(sendreq->req_send.req_base.req_ompi.req_persistent &&                    \
+               (0 != sendreq->req_send.req_base.req_count) ) {                          \
                 /* rewind convertor */                                                  \
                 size_t offset = 0;                                                      \
                 ompi_convertor_set_position(&sendreq->req_send.req_convertor, &offset); \