I don't think so, for a couple of reasons.
* I want to make it really obvious that git-clean did nothing. Spewing piles
of output quickly obscures the error message, and doesn't convey "git-clean
did nothing" at a glance.
* -n takes time, especially with a large working copy. Doing nothing takes
very little time. The original use case motivating this patch came from the
idea of a git $HOME, and wanting to make sure git-clean won't delete
everything untracked in $HOME. git-clean -n would take a long time here,
and I don't want to do it implicitly, particularly if I meant to clean a git
repository *under* $HOME.
- Josh Triplett