trydiff: make 'revs' ignored if opts.git is set Instead of setting revs=None to prevent the call to diffline() when opts.git is set, explicitly do not call the function in the git case.

trydiff: remove unused argument to diffline() Now that diffline no longer knows about copies/renames, it only needs one argument for the path.

trydiff: move git-header code out of diffline function This collects more of the code for writing git headers in a single place and makes diffline() close on a few variables less.