Don't assume list? means (listof char?).
Don't assume list? means (listof char?).

This is a "hot fix" for commit 68ec385d breaking when used by the
markdown package.

This isn't the most-efficient way to do it, however. Although it fixes
the problem it causes a performance threshold test in markdown lib to
fail.

guildhall/guile-parallax,taktoa/guile-parsack,taktoa/guile-parallax