app/rest/changes lists commits outside vcs root

Hi,

We have a teamcity server that makes a new build after each commit. I am making a service that takes those builds and runs a few tests on them. If the service finds a build that fails a test it tries to determine the last revision that passed. To accomplish that the service needs to trigger builds on team city. As not all commits influence a given buildtype I need to get a list of commmits that do. So I use

/app/rest/changes?BuildTypeId=bt123

In this list however, commits show up that only affect files outside the vcs root for the specified buildtype. When I trigger a build using the modificationId that corresponds to the commit that only affects files outside the vcs root, and look at the build details when it is finished, the display-version is set to the last revision that did have an impact. Inspecting the changes for the build yields zero changes:

app/rest/changes?build=id:12345

Am I correct to assume changes should only be listed for a specific buildtype when the commit actually changes at least one file in the vcs-root?

Thanks, Bas