#1499 added very initial support for passing a tolerance to datasource features_at_point. However, it was only implemented for postgis, and needs to be done for all other datasources, along with tests. A test was added for the shape.input, but only passed because the shape.input had a bug whereby points were not actually filtered by bbox (until 02bb955 /#1630).
properly support tolerance in shape filter_at_point - refs #1640
finished up in a3eaebd and 653e9e7. followup at #1861