will try to explain better here, i finished the space in the changeset comment.
What im trying to check here is if motor_vehicle=* (2nd layer in the hierarchy after vehicle=*) overrides all of his subtags if specified in OSM. 
For this test, expected behaviour would be that cars cant go here, but motorcycles can. 
This is helpful to clarify what tagging scheme is needed for ZTLs and related ways. The general ZTL has this kind of restricion. Specific ZTL (Zona T, Zona U and the two ZTLS) would have motor_vehicle=permit, but a lot of exceptions for goods and similar, which would create a similar situation (goods=* is under motor_vehicle in the hierarchy). 
Why did i chose this street? Because A) Its a ZTL and not a random street; and B) this area only has one entry, via Bertoloni, all other ways are oneways/pedestrian, therefore making it easy to spot routing mistakes