dict-sql: Do not increment on set

When merging sets do not use increment mode in builder.

src/lib-dict/dict-sql.c

@@ -1263,7 +1263,7 @@ static void sql_dict_set(struct dict_transaction_context *_ctx,
 		t_array_init(&build.fields, 1);
 		build.extra_values = &values;
 		build.key1 = key[0];
-		build.inc = TRUE;
+		build.inc = FALSE;
 
 		field = array_append_space(&build.fields);
 		field->map = ctx->prev_set_map;