If I got it correctly, the removal of the sticky date tags happens in AbstractCvs.postCheckout, where the path workspace.child(module.getCheckoutName()) is used.

Now, if only one module is checked out and the local name is not set, the project is actually checked out in the root directory of the workspace, while module.getCheckoutName() will return the CVS module name.

Failing to cleanup the sticky date tags causes the M2 release plugin to fail