JabRef 5.0.0-dev--2019-10-31----ac7875a96
Linux 5.0.0-32-generic amd64
Java 12.0.2

JabRef version on

• [ X] I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

Steps to reproduce the behaviour:

1. Fill out Author and date.
2. Author in the form "Surname, Firstname."
3. Preferences set the default key pattern to "[auth4:lower]-[year]"
4. Hit "generate key"
5. The result is firs-2018.
6. It used to be - correctly - "surn-2018"