huspell-en doesn't handle apostrophes
Currently words like "isn't" are not handled correctly:
% echo echo "isn't" | hunspell -d en_US -i utf-8
Hunspell 1.7.1
*
& isn 9 5: sin, ins, ism, is, in, inn, ion, isl, is n
*
Changing WORDCHARS in the .aff file to contain an apostrophe solves the problem:
WORDCHARS 0123456789'
after:
% echo echo "isn't" | hunspell -d en_US -i utf-8
Hunspell 1.7.1
*
*
Fedora has been shipping a patch for this for 13 years: https://src.fedoraproject.org/rpms/hunspell-en/blob/rawhide/f/hunspell-en-allow-non-typographical.marks.patch