We have many builds configured for the same git repository with VCS trigger rules that look like this:
There is also a branch filter, like this:
Recently I notice that every build on a new branch seems to trigger on every commit. On the Overview tab the build says it was triggered by git, but on the Changes tab it says "There are no changes found." If TeamCity can see that there are no changes why not cancel the build?
I don't think this always happened - it may have started since the upgrade to TeamCity 2018.2.