Saw this rabbit in our front garden last night and again today. It wasn't timid, I walked past it on the path and it didn't spook, just hopped away a bit. Looks happy enough nibbling the grass, doesn't seem to be in any distress.
In an inner city area, not the kind of place I'd expect to see wild rabbits.
Looks like a pet to me too. Are you able to catch it and either look after it yourself for a few days while you ask around, or take it to a shelter? A trusting pet rabbit will be very vulnerable to dog attacks, cruelty, being run over, the cold....I doubt he will last the night if he's left.
We've got one in the alley behind our house! Black as well, quite small. I thought ours was an escapee that's really good at hiding from the local cats, DP thinks its owners 'let it out for a walk' on its own...
In a built up area I would say pet. Ex-pet rabbits in our rural area have caused our wild rabbit population to breed a lot more non-brown varieties. They're usually hunted quicker but some make it to carry on the domestic colour lines.