[master] c2beacdfd shard director: handle nested workspace overflow

[Nils Goroll]

commit c2beacdfdc4dbad0f73a5dfda9bd05ebf0133261
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Mon Jan 18 12:50:03 2021 +0100

    shard director: handle nested workspace overflow
    
    Propagate upwards any workspace allocation failure of the
    recursive shard_param_task_l() case.

diff --git a/vmod/vmod_directors_shard.c b/vmod/vmod_directors_shard.c
index ce52bb5e8..2a214279d 100644
--- a/vmod/vmod_directors_shard.c
+++ b/vmod/vmod_directors_shard.c
@@ -945,6 +945,9 @@ shard_param_task_l(VRT_CTX, const void *id, const char *who,
 	else
 		p->defaults = shard_param_task_l(ctx, pa, pa->vcl_name, pa);
 
+	if (p->defaults == NULL)
+		return (NULL);
+
 	return (p);
 }