Retrieve nullifiers for all unconfirmed notes.

Previously we were retrieving nullifiers for notes that were not
marked spent, but not checking against whether the spending
transaction had been included in a block.

zcash_client_sqlite/src/wallet.rs

@@ -470,13 +470,21 @@ pub fn get_witnesses<P>(
     Ok(res)
 }
 
+/// Retrieve the nullifiers for notes that the wallet is tracking
+/// that have not yet been confirmed as a consequence of the spending
+/// transaction being included in a block.
 pub fn get_nullifiers<P>(
     wdb: &WalletDB<P>,
 ) -> Result<Vec<(AccountId, Nullifier)>, SqliteClientError> {
     // Get the nullifiers for the notes we are tracking
     let mut stmt_fetch_nullifiers = wdb
         .conn
-        .prepare("SELECT id_note, account, nf FROM received_notes WHERE spent IS NULL")?;
+        .prepare(
+            "SELECT rn.id_note, rn.account, rn.nf, tx.block as block
+            FROM received_notes rn
+            LEFT OUTER JOIN transactions tx
+            ON tx.id_tx = rn.spent
+            WHERE block IS NULL")?;
     let nullifiers = stmt_fetch_nullifiers.query_map(NO_PARAMS, |row| {
         let account = AccountId(row.get(1)?);
         let nf_bytes: Vec<u8> = row.get(2)?;