checkout folder not cleaned before build

I have a single VCS root and a checkout folder that is shared between a number of different build configurations.

The VCS root is marked to always cleanup the checkout folder, with a clean policy of "all non-ignored" untracked files: My build generates a folder which is named TeamCityOutput under the checkout dir. This folder is definitely not ignored, but still it is not being cleaned before a build.

I suspect that what happens is that since the checkout folder is shared between a number of build configurations, and since the same git SHA1 (change) is used, the cleanup will not be performed (even though it's marked to "always" run).

Can someone verify that this is indeed correct?

For example, if builds A and B both execute on the same agent and the current changeset (git SHA1) is 2c18106d06c02244c1aeea9520410907b7cd7e7b, no cleanup will be made. that is my theory at least.