Upstream patch, whitespace altered to apply.

diff --git a/src/kdc/do_as_req.c b/src/kdc/do_as_req.c
index 46b5fa1..464cb6e 100644
--- a/src/kdc/do_as_req.c
+++ b/src/kdc/do_as_req.c
@@ -741,6 +741,8 @@ prepare_error_as (struct kdc_request_state *rstate, krb5_kdc_req *request,
 		pad->contents = td[size]->data;
 		pad->length = td[size]->length;
 		pa[size] = pad;
+		td[size]->data = NULL;
+		td[size]->length = 0;
 	    }
 	    krb5_free_typed_data(kdc_context, td);
 	}
