merge ignores --no-commit in fast-forward case

Bug or feature?

Three possible solutions that I see:

  2) Refuse to do anything if user gives --no-commit and merge is fast- 
forward
  3) Document this behavior in the manpage
  4) Quietly set deny_non_fast_forward when --no-commit was given

A fourth solution would be to not change anything, but users usually  
have a reason for using --no-commit, and if git commits behind their  
backs anyway that's just not nice.

tom