[rpc] Filter out unrelated transactions

For some reason while doing the "remove blockchain from wallet PR" I
changed the tests around in what I thought was a benign way. But it
meant (apparently) that both parties "test_sync_double_receive" were
using the same "blockchain". This meant that when the blockchain was RPC
they both imported their addresses to it and got each other's results
when syncing. This bugged out the sync and this commit fixes that.

src/blockchain/rpc.rs

@@ -318,22 +318,24 @@ impl WalletSync for RpcBlockchain {
             }
         }
 
-        let current_utxos: HashSet<_> = current_utxo
+        // Filter out trasactions that are for script pubkeys that aren't in this wallet.
+        let current_utxos = current_utxo
             .into_iter()
-            .map(|u| {
-                Ok(LocalUtxo {
-                    outpoint: OutPoint::new(u.txid, u.vout),
-                    keychain: db
-                        .get_path_from_script_pubkey(&u.script_pub_key)?
-                        .ok_or(Error::TransactionNotFound)?
-                        .0,
-                    txout: TxOut {
-                        value: u.amount.as_sat(),
-                        script_pubkey: u.script_pub_key,
-                    },
-                })
-            })
-            .collect::<Result<_, Error>>()?;
+            .filter_map(
+                |u| match db.get_path_from_script_pubkey(&u.script_pub_key) {
+                    Err(e) => Some(Err(e)),
+                    Ok(None) => None,
+                    Ok(Some(path)) => Some(Ok(LocalUtxo {
+                        outpoint: OutPoint::new(u.txid, u.vout),
+                        keychain: path.0,
+                        txout: TxOut {
+                            value: u.amount.as_sat(),
+                            script_pubkey: u.script_pub_key,
+                        },
+                    })),
+                },
+            )
+            .collect::<Result<HashSet<_>, Error>>()?;
 
         let spent: HashSet<_> = known_utxos.difference(&current_utxos).collect();
         for s in spent {