Merge pull request #9600 from SharzyL/fix_nix_copy

fix: nix copy ssh-ng:// not respecting --substitute-on-destination
(cherry picked from commit b1c633c6bb2e2dbc8a2891edf0d0c6f9d31d890b)
Change-Id: I77356d14a9011d6dc4cf64776995f7590d918874

src/libstore/remote-store.cc

@@ -225,7 +225,7 @@ StorePathSet RemoteStore::queryValidPaths(const StorePathSet & paths, Substitute
         conn->to << WorkerProto::Op::QueryValidPaths;
         WorkerProto::write(*this, *conn, paths);
         if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 27) {
-            conn->to << (settings.buildersUseSubstitutes ? 1 : 0);
+            conn->to << maybeSubstitute;
         }
         conn.processStderr();
         return WorkerProto::Serialise<StorePathSet>::read(*this, *conn);