fix(resharding) - fix loading shards when no resharding is scheduled (#…

…12808)

The issue was that since `STABLE_PROTOCOL_VERSION` was higher than
what's in mainnet the implementation was including the current shard
layout in the calculation. Additionally the current shard layout is V1
and it has non-unique shard ids which made it seem like there is a
resharding pending.

The fix is to exclude the head shard layout from the calculation.

chain/epoch-manager/src/adapter.rs

@@ -437,18 +437,21 @@ pub trait EpochManagerAdapter: Send + Sync {
         head_protocol_version: ProtocolVersion,
         client_protocol_version: ProtocolVersion,
     ) -> Result<HashSet<ShardUId>, Error> {
+        let head_shard_layout = self.get_shard_layout_from_protocol_version(head_protocol_version);
         let mut shard_layouts = vec![];
         for protocol_version in head_protocol_version + 1..=client_protocol_version {
             let shard_layout = self.get_shard_layout_from_protocol_version(protocol_version);
+            if shard_layout == head_shard_layout {
+                continue;
+            }
 
             let last_shard_layout = shard_layouts.last();
-            if last_shard_layout == None || last_shard_layout != Some(&shard_layout) {
+            if last_shard_layout != Some(&shard_layout) {
                 shard_layouts.push(shard_layout);
             }
         }
 
         let mut result = HashSet::new();
-        let head_shard_layout = self.get_shard_layout_from_protocol_version(head_protocol_version);
         for shard_uid in head_shard_layout.shard_uids() {
             let shard_id = shard_uid.shard_id();
             for shard_layout in &shard_layouts {

chain/epoch-manager/src/tests/mod.rs

@@ -3786,6 +3786,22 @@ fn test_get_shard_uids_pending_resharding_none() {
     assert_eq!(shard_uids.len(), 0);
 }
 
+/// Test there are no ShardUIds pending resharding when there are no planned
+/// reshardings in the simple nightshade v3 shard layout that is used in prod.
+///
+/// This test checks that when then protocol version is changing but the shard
+/// layout is not, no shard is pending resharding.
+#[test]
+fn test_get_shard_uids_pending_resharding_simple_nightshade() {
+    let v3 = ShardLayout::get_simple_nightshade_layout_v3();
+    let shard_uids = test_get_shard_uids_pending_resharding_base(&[v3.clone(), v3]);
+    assert_eq!(shard_uids.len(), 0);
+
+    let v4 = ShardLayout::get_simple_nightshade_layout_v4();
+    let shard_uids = test_get_shard_uids_pending_resharding_base(&[v4.clone(), v4]);
+    assert_eq!(shard_uids.len(), 0);
+}
+
 /// Test that there is only one ShardUId pending resharding during a single
 /// resharding.
 #[test]