I regularly ssh to one of my OS X boxes. I have configured ssh key-based authentication i.e. added my client-end
~/.ssh/id_rsa.pub to server-end
~/.ssh/authorized_keys2 with restricted enough permissions. This setup has worked fine for years over multiple OS X versions.
However, upgrading to OS X 10.9 Mavericks broke this setup. ssh login prompts for password. Logging in with password works but I want passwordless key-based authentication.
(I know the solution to this now. Documenting it here in case it helps others.)