grep: restore usage of --include/--exclude options
The refactor in 4a73df6eb67d accidentally forgot to transform the opts
argument for walkopts into a byteskwargs. This resulted in its options
being ignored. In particular, the -X/-I pair of options was missing.
A simple fix restores its usage. Tests included, of course.
edition = "2018"
max_width = 79
wrap_comments = true
error_on_line_overflow = true