Logging in with email generates errors in log #3038

Hi!

I've seen on my Nextcloud-server that if a user logs in with their registered e-mail, then they are able to logging in, but it throws errors to the server log. I've seen this in all versions up to 10.0.2, and I'm still experiencing the issue. If I ask users to log in with username only, then there's no errors in the log anymore.

Server configuration

Operating system: Ubuntu 16.04.1

Web server: Apache

Database: Mysql 14.14

PHP version: 7.0.8

Nextcloud version: 10.0.2

Updated from an older Nextcloud/ownCloud or fresh install: Clean install

Where did you install Nextcloud from: Downloaded zip file from webpage

Log entries:
Warning core Login failed: 'marius@domain' (Remote IP: '10.0.0.0') 2017-01-12T07:02:53+00:00 --
Warning core Login failed: 'rolf@domain' (Remote IP: '10.0.0.0') 2017-01-12T06:59:17+00:00 --
Warning core Login failed: 'rolf@domain' (Remote IP: '10.0.0.0') 2017-01-12T06:59:11+00:00 --
Warning core Login failed: 'rolf@domain' (Remote IP: '10.0.0.0') 2017-01-12T06:59:11+00:00 --
Warning core Login failed: 'rolf@domain' (Remote IP: '10.0.0.0') 2017-01-12T06:59:10+00:00 --
Warning core Login failed: 'rolf@domain' (Remote IP: '10.0.0.0') 2017-01-12T06:59:11+00:00 --
Warning core Login failed: 'rolf@domain' (Remote IP: '10.0.0.0') 2017-01-12T06:59:10+00:00 --