The bots scan the files in a PR when it is created, and updates the set of labels according to rules based on the files included in the PR.

However, if the author adds additional commits, that touch other files, the set of labels is not updated.

A typical problem is that someone realizes that a build system change is needed, and adds build changes as a follow-up commit. But since this was not in the original commit, the `build` label is never added.

Skara bots should check for each additional commit if new files are added, and if so, add proper labels if needed.