Clean up pre_commit_callback wrapping code

ledger/src/blockstore_processor.rs

@@ -180,14 +180,12 @@ pub fn execute_batch(
     let is_block_producing_unified_scheduler = pre_commit_callback.is_some();
     let pre_commit_callback = pre_commit_callback.map(|wrapped_callback| {
         || {
-            wrapped_callback()
-                .inspect(|&maybe_index| {
-                    if let Some(index) = maybe_index {
-                        assert!(transaction_indexes.is_empty());
-                        transaction_indexes.to_mut().push(index);
-                    }
-                })
-                .map(|_| ())
+            wrapped_callback().map(|maybe_index| {
+                assert!(transaction_indexes.is_empty());
+                transaction_indexes.to_mut().extend(maybe_index);
+                // Strip the index away by implicitly returning (), now that we're done with it
+                // here (= `solana-ledger`), to make `solana-runtime` not bothered with it.
+            })
         }
     });
 

unified-scheduler-pool/src/lib.rs

@@ -459,7 +459,7 @@ impl TaskHandler for DefaultTaskHandler {
                 if handler_context.transaction_status_sender.is_some() {
                     // Adjust the empty new vec with the exact needed capacity, which will be
                     // filled inside `execute_batch()` below. Otherwise, excess cap would be
-                    // reserved on `.push(transaction_index)` in it.
+                    // reserved on `.extend()` in it.
                     vec.reserve_exact(1);
                 }
                 vec