The succeeding character was needed to avoid miscolorings due to nano
getting confused about starts and ends.  But since commit 7ef5c532,
nano should be getting the starts and ends always right, so... undo
"temporary" commit 7b2ea405 from two years ago.

This addresses https://savannah.gnu.org/bugs/?51526.
Reported-by: <exodus6395@googlemail.com>