CI emails may contain a recipient's address multiple times

If a CI has sendtoauthors enabled, it will send email reports to the authors/committers of the tested commits.

If there is an overlap between these authors, and the addresses mentioned in errorrecipients, the CI system makes no attempt to remove the overlap; the same address may appear in both To: and CC:

Although I'm not sure if it causes any harm, this should be fixed so that addresses will only appear once.