Hi Steve,
Unless you know better, I'd say it was time or nearly time to merge that branch back to trunk.
Agreed.
The only slightly odd behaviour for me is at: http://www.openstreetmap.org/?mlat=51.612512&mlon=-3.961642&zoom=18&layers=B...
..where, if I approach on the southern stub from the traffic lights on Oystermouth Rd (A4067) I'd expect to be told "turn right" onto the oneway section of B4290. But I get no announcement.
That northeasterly-bound section of B4290 isn't a single way because of bus-route issues, but I made a "through_route" relation to span across the junction "just in case". It made no difference.
But as a left turn isn't actually allowed there, perhaps the GPS doesn't bother to tell you to turn right as it "knows" you can't turn left? Cheers, Mark