Course search doesn't find course when search include "-" with a space before or after

Hi,

the search course feature is useful, but it does not find courses when the search sentence include a - sign, with a space before and/or after.

As an exemple, if you have a course named "Présentation - Moodlebox" :

• "Présentation - Moodlebox" (space before and after) : does not find course
• "Présentation -" (space before) : does not find course
• "- Moodlebox" (space after) : does not find course
• "Présentation Moodlebox" : does find course

If you have a course named "Présentation-Moodlebox" (without space), it find it when you search "Présentation-Moodlebox".

Same problem on 3.3 dev, tested on qa.moodle.net.