Bug 792157 - Cannot create account with different currency

Restore force-insert logic that had gotten lost in the C++ conversion.

libgnucash/backend/sql/gnc-commodity-sql.cpp

@@ -217,8 +217,8 @@ GncSqlCommodityBackend::commit (GncSqlBackend* sql_be, QofInstance* inst)
     g_return_val_if_fail (sql_be != NULL, FALSE);
     g_return_val_if_fail (inst != NULL, FALSE);
     g_return_val_if_fail (GNC_IS_COMMODITY (inst), FALSE);
-
-    return do_commit_commodity (sql_be, inst, FALSE);
+    auto in_be = instance_in_db(sql_be, inst);
+    return do_commit_commodity (sql_be, inst, !in_be);
 }
 
 /* ----------------------------------------------------------------- */

libgnucash/backend/sql/gnc-sql-backend.cpp

@@ -811,6 +811,8 @@ GncSqlBackend::object_in_db (const char* table_name, QofIdTypeConst obj_name,
 
     /* WHERE */
     PairVec values{get_object_values(obj_name, pObject, table)};
+    /* We want only the first item in the table, which should be the PK. */
+    values.resize(1);
     stmt->add_where_cond(obj_name, values);
     auto result = execute_select_statement (stmt);
     return (result != nullptr && result->size() > 0);