[@pdalpra]: http://github.com/pdalpra
[2107]: https://github.com/sbt/sbt/issues/2107
[2114]: https://github.com/sbt/sbt/pull/2114

### Fixes with compatibility implications

### Improvements

### Bug fixes

- Add an Append.Sequence instance for List, allow +=/++= on `developers` SettingKey [#2107][2107]/[#2114][2114] by [@pdalpra][@pdalpra]