carrot_impl: fix key image scanning in view-only and burned zombie outputs

src/wallet/wallet2.cpp

@@ -2368,7 +2368,7 @@ void wallet2::scan_key_image(const wallet::enote_view_incoming_scan_info_t &enot
 {
   ki_out = std::nullopt;
 
-  if (m_multisig || m_background_syncing) // no spend privkey
+  if (m_multisig || m_background_syncing || m_watch_only) // no complete spend privkey
     return;
 
   // if keys are encrypted, ask for password
@@ -2524,6 +2524,11 @@ void wallet2::process_new_scanned_transaction(
         << print_money(burning_td->amount()) << " in tx " << burning_td->m_txid << ", received output ignored");
       continue;
     }
+    else if (burning_td)
+    {
+      // This new, better transfer "burns" the other one
+      set_spent(ot_it->second, height);
+    }
 
     // update local received money counts
     const rct::xmr_amount extra_received_money = enote_scan_info->amount - (burning_td ? burning_td->amount() : 0);