I came across this sign when walking in Ruoholahti, Helsinki. What I find interesting here is that the construction work has rendered the "no dogs" sign obsolete.
Indeed, in the pole in this small greenery area we have the standard "no dogs" sign as used by the city of Helsinki. But it is now in an area where dogs can't get to, at least without maybe a human lifting them over a fence? So the construction site indexes, like the fences around the area, make the sign obsolete.
We note here that the sign is not negated, as this is clearly still a "no-dogs zone". Furthermore the dog sign has not been removed, so perhaps the area should return later on to be a dog-accessible but not-allowed area?