For zero length persistent request do not reposition the convertor as

it is not initialized.

This commit was SVN r10386.

ompi/mca/pml/dr/pml_dr_sendreq.h

@@ -249,7 +249,8 @@ do {
     if( sendreq->req_send.req_base.req_free_called ) {                              \
         MCA_PML_DR_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_bytes_packed) ) {                            \
             /* rewind convertor */                                                  \
             size_t offset = 0;                                                      \
             ompi_convertor_set_position(&sendreq->req_send.req_convertor, &offset); \