French custom_group title can cause SQL error in CiviCase

How to reproduce:

• create a custom group for Activities, with title: L'activité
• add a field in that group
• in a Case, add an activity, enter a value in that custom field (shouldn't be necessary, but that's what I tested)
• in the Case list of Activities (at the bottom of the screen), click on the "view" link for that activity (it opens a popup to view the activity).

The popup will cause a network error, because of an SQL error.

This is a potential security issue, but the attacker needs full admin permissions to manage custom fields (it could affect a SaaS provider, for example).