wp-cli/wp-cli — pull request #162 by nb (2012-09-08 08:11:37+00:00)
Title: Guess WordPress root if we're in a plugins directory

This will allows to run wp-cli from a directory of
a plugin.

If wp-content isn't inside the WordPress this
won't work, but since it's not in a WordPress root
it won't work anyway, so I'd risk it.