unwrap the correct value in the parallel code

Author: rsmyth-ecmi

compiler/rustc_query_system/src/query/plumbing.rs

@@ -285,10 +285,12 @@ where
                     // We didn't find the query result in the query cache. Check if it was
                     // poisoned due to a panic instead.
                     let lock = query.query_state(qcx).active.get_shard_by_value(&key).lock();
-                    lock.get(&key).expect_job(query.name());
-                    panic!(
-                        "query result must in the cache or the query must be poisoned after a wait"
-                    );
+                    match lock.get(&key) {
+                        poisoned @ Some(QueryResult::Poisoned) => poisoned.expect_job(query.name()),
+                        _ => panic!(
+                            "query result must in the cache or the query must be poisoned after a wait"
+                        ),
+                    }
                 })
             };