TeamCity Enterprise 9.1.7 checked out wrong VCS commit - NOV 22, 2016

Hello.

We first notice this issue when we use 8.x. Now this issue occurs frequency and become super annoying.

We have about 500 VCS Roots. This is become a major issue to our CI process today.

We are now using TeamCity Enterprise 9.1.7.

We have a bunch of build projects each have 28 VCS Roots, each VCS Root -> General Settings -> Default Branch contains a system parameter %system.default_branch%

We don't use agent checkout

About Problematic Build:

1. In Build Log -> Parameter tab: 'system.default_branch' is showing 'refs/heads/release'

2. In Build Log -> Changes tab: How ever the Revision of this VCS Root is not the latest commit of refs/heads/release

3. Re-build with clean-checkout doesn't help. TeamCity still checkout the old commit of that branch.

4. Change system parameter 'system.default_branch' from 'refs/heads/release' to 'release' will resolve this issue. 

5. This issue may happen (about 10% chance) when user did merged code into the branch of system parameters.

What kind of information should we provide to help you address this issue?