Is there an issue with `sudo -k' ?

There was a report via Twitter yesterday [1] that said

        "Commands hang on ' /bin/sh -c sudo -k'. This is Ubuntu 10.04,
         Ansible 0.9 from the PPA"

IIRC, this was dicussed somewhere not terribly long ago (Twitter, IRC,
Github, mailing-list -- my memory fails me, and I can't find it.) It was
due either to /bin/sh not being quite compatible or an issue with the
'-k' switch to sudo.

Can anybody help Paul? Is there a problem and/or a solution?

Thanks,

        -JP

[1] https://twitter.com/PaulNendick/status/279193803733225472