The potential linebreaks at commas in code lines were not inserted due
to latex kernel macro ``\@noligs`` which is issued by fancyvrb.sty
during its line processing. From the default `` `<>,'- ``, only the
backtick is left to be handled by ``\@noligs`` because the others are
either already replaced by a macro by Pygments, or (only the comma) made
active by sphinx.sty to insert potential linebreaks.