Old feature branches rebuild triggers, but should not

Hello all,

I have a project with multiple git repositories. I use cross-repo feature branches often, and found an ugly behaviour which I can't change.

For many feature branches, not all repositories contain the "feature branch" itself. F.e. project (repoa, repob, repoc) may have a bugfix branch "bug_666".
The bug was fixed on repoa, with the only branch created in there: repoa:bug_666. Consequently, repob, repoc are used with their "master" branches to build such a feature build.

That bug666 was fixed months ago, but any commit in repob/repoc on "master" triggers that "bug_666" feature build.

Situation gets uglier and uglier, since I have tons of these branches, and now basicaly any change on "master" causes a sporadic generation of ~100 useless builds for each of the "old" branches.

Obviously I could fix this by removing bug_666 branch physically, but this is not a good solution.

Could that be some wrong setup on my TC (v. 8.0.5), or is this an expected behaviour?