Retain request dependencies only when discovery supplies the answer

tests/scenario/mod.rs

@@ -356,7 +356,7 @@ fn change(case: Case, warm: &mut Harness, tree: &mut Tree, plan: &Plan, rng: &mu
 /// out by hand. A failure is a lead; the fast test that replaces it has to be
 /// buildable from what the failure printed.
 fn describe(id: WidgetId, h: &Harness) -> String {
-    let rules = h.rsc.widgets().size_rules(id);
+    let rules = h.rsc.widgets().size_rules(id).clone();
     // A bound prints as itself: a failure is reproduced from what it printed,
     // and a rule shown as "no rule" cannot be written out again.
     let rule = |r: SizeRule| match r {