ompi/pml/ucx: Fix uninitialized UCX request field.

Signed-off-by: Artem Polyakov <artpol84@gmail.com>

ompi/mca/pml/ucx/pml_ucx_request.c

@@ -166,7 +166,8 @@ static int mca_pml_ucx_persistent_request_free(ompi_request_t **rptr)
         mca_pml_ucx_persistent_request_detach(preq, tmp_req);
         ucp_request_free(tmp_req);
     }
-    if (MCA_PML_BASE_SEND_BUFFERED == preq->send.mode) {
+    if ((preq->flags & MCA_PML_UCX_REQUEST_FLAG_SEND) &&
+         (MCA_PML_BASE_SEND_BUFFERED == preq->send.mode)) {
         OBJ_RELEASE(preq->ompi_datatype);
     }
     PML_UCX_FREELIST_RETURN(&ompi_pml_ucx.persistent_reqs, &preq->ompi.super);