Whole word search generates errors when a term name contains a slash

Steps to reproduce :
1. Create a vocabulary
2. In vocabulary edition, check "Only match Autocategorised terms on whole words"
3. Create a term in this vocabulary. For example "Research / University"
4. Create a content
5. Attach this type of this content to the vocabulary
6. In the vocabulary, click the "Run Autocategorise" button

You will get this error :
preg_match() [function.preg-match]: Unknown modifier 'n' in /var/www/drupal/sites/all/modules/autocategorise/autocategorise.module on line 403.