Certain special characters can break pretty permalinks

[andrewspittle]

When adding the è character to a post title the permalink is no longer pretty.

To reproduce, create a title such as "Jornades a l’ENSSIB sobre els projectes de bibliografia del llibre antic a l’època de la digitalització"

The permalink generated will end in:

/jornades-a-l%E2%80%99enssib-sobre-els-projectes-de-bibliografia-del-llibre-antic-a-l%E2%80%99epoca-de-la-digitalitzacio/

The permalink will still work when clicked on but ideally shouldn't contain the extra character junk.

[scribu]

The problem isn't the è, but the ’ character.

Marking as dup of #3843