Live vehicle positions: jumping on the map

[stadtnavimanager]

Comment @hbruch : Workaround implementiert: HSLdevcom/gtfsrthttp2mqtt#32 er wartet noch auf Review durch HSL, bevor ich ihn deployen kann (ich möchte vermeiden, einen Fordk davon anzulegen). Ich habe Joel nochmal angepingt.

[hbruch]

Above change is now deployed via stadtnavi/digitransit-ansible@d21650b and seems to work well.

Note: though we poll every two seconds for a new version of VVS's vehicle positions feed, major changes in their feed only seem to happen every 30 seconds. I suppose position changes occuring in between these 30s to be delivered by a second service running behind the reverse proxy which has a slightly different state.