Allowing to reserve 0 bytes in njs_chb_reserve() for consistency.
diff --git a/src/njs_chb.c b/src/njs_chb.c
index 718cfe6..6c54ec8 100644
--- a/src/njs_chb.c
+++ b/src/njs_chb.c
@@ -34,10 +34,6 @@
 {
     njs_chb_node_t  *n;
 
-    if (njs_slow_path(size == 0)) {
-        return NULL;
-    }
-
     n = chain->last;
 
     if (njs_fast_path(n != NULL && njs_chb_node_room(n) >= size)) {