Pull the corresponding osrm-backend revision by release tag:
Pull the corresponding osrm-backend revision by release tag:

- Update environment variable to resemble https://github.com/mapnik/mapnik-packaging/pull/184

KnockSoftware/node-osrm,KnockSoftware/node-osrm,Project-OSRM/node-osrm,oxidase/node-osrm,Project-OSRM/node-osrm,KnockSoftware/node-osrm,oxidase/node-osrm,oxidase/node-osrm,Project-OSRM/node-osrm,KnockSoftware/node-osrm