hub: `hub clone org/repo` private repo, fails unless explicit https

I’m a member of organization org which has private repository repo:

For hub clone org/repo:

github.com username: lukedmor
github.com password for lukedmor (never stored): 
Cloning into 'repo'...
fatal: remote error:
 repository not found.

However, hub clone https://github.com/org/repo does work correctly.