Attribute(name, value, minzoom) writes attribute on all zoom levels

[Nakaner]

The minzoom argument of the function Attribute(name, value, minzoom) is not working.

How to reproduce:

• Download a motorway: curl https://api.openstreetmap.org/api/0.6/way/4231749/full | osmium cat --input-format xml --output-format pbf -o w4231749.osm.pbf -
• Create vector tiles from it: ./tilemaker --input w4231749.osm.pbf --output /tmp/tiles/ --bbox 8.2802,48.8782,8.3682,48.9414 --process resources/process-openmaptiles.lua --config resources/config-openmaptiles.json
• Open the tile on zoom level 8 with ogrinfo: ogrinfo -ro -al MVT:/tmp/tiles/8/133/88.pbf

Ogrinfo will print a linestring geometry with a surface attribute. However, the Tilemaker process file says that the attribute is supposed to be written on zoom level 9 and larger only.

The bug was introduced by commit d62c480debf6c38cd5d2c6339bfaa995b05fb9f2 by @cldellow.

[cldellow]

Ack, thank you for diagnosing the breaking commit and for the excellent reproduction steps.

672 should fix that, and also adds tests to catch future regressions. I think minzooms greater than 7 were not being honoured correctly.