Commit Briefs
use get_worktree_paths_from_argv consistently; improves add/rm edge cases
Double 'got rm' becomes a no-op like double 'got add' already is, and 'got add' of an already staged file is now an error.
got_error_set_errno: take a char arg to pass to got_error_prefix_errno
$> got rm a got: : No such file or directory becomes $> got rm a got: /path/to/a: No such file or directory