Fix for distinct function

[Mr4Mike4]

Fixed the bug in the distinct function with three arguments

[cla-bot]

Realm welcomes all contributions! The only requirement we have is that, like many other projects, we need to have a Contributor License Agreement (CLA) in place before we can accept any external code. Our own CLA is a modified version of the Apache Software Foundation’s CLA. Our records show that CLA has not been signed by @Mr4Mike4. Please submit your CLA electronically using our Google form so we can accept your submissions. After signing the CLA you can recheck this PR with a @cla-bot check comment. The GitHub usernames you file there will need to match that of your Pull Requests. If you have any questions or cannot file the CLA electronically, make a comment here and we will be happy to help you out.

[cmelchior]

Hi @Mr4Mike4 Thank you very much for this. If you sign the CLA, I can merge this.

[Mr4Mike4]

@cla-bot check

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!

[Mr4Mike4]

Hi @cmelchior . I signed the CLA. Please merge my pull request

[bmunkholm]

This just needs an update in the changelog. Adding a test that demonstrates the fix would also be great.