Due to lack of documentation regardingonly-new-issues feature, I'd like to know how does it really work.
I thought the desired workflow is following, considering such branch tree (topic has 3 commits A, B, C and open Pull Request on Github to desired master branch):

  A---B---C topic /D-- master

Whole pull request will be checked against a head of the master. So only those issues that come with the topic branch will be reported by the linter.
In my case, the linter doesn't report anything even that I have issues done on purpose in the topic branch.

To conclude, how does theonly-new-issues work? I'd really like to go with the suggestion from the docs that says to not scan the whole repo but only the newest changes.