Readd mandatory prefix to avoid bbox filter collision

Author: bagage

src/overpass_api/statements/id_query.h

@@ -75,8 +75,8 @@ class Id_Query_Statement : public Output_Statement
     virtual std::string dump_ql_in_query(const std::string& indent) const
     {
       std::vector< uint64 >::const_iterator it = refs.begin();
-        
-      std::string result = "(";
+
+      std::string result = "(id:" + ::to_string(refs.size()) + ",";
       if (it != refs.end())
         result += ::to_string(*it++);
       while (it != refs.end())