D5620: grep: don't look up copy info unless --follow is given

[Yuya Nishihara]

> -            if fn in skip:
> +            copy = None
> +            if follow:
> +                try:
> +                    copied = flog.renamed(fnode)
> +                except error.WdirUnsupported:
> +                    copied = ctx[fn].renamed()
> +                copy = copied and copied[0]
>                  if copy:
> -                    skip[copy] = True
> -                continue
> +                    copies.setdefault(rev, {})[fn] = copy
> +                    if fn in skip:
> +                        skip[copy] = True
> +                        continue
>              files.append(fn)

Did you intentionally move `if fn in skip: continue` under `if follow`?
The skip dict has wider scope.