Ref T11823. See PHI68. T11823 has a full description of this issue and a plan to fix it, but the full plan is relatively complicated.
Until that can happen, provide a workaround for the biggest immediate issue, where multiple copies of a ref cursor can cause executeOne() to throw, since it expects a single result. In practice, these copies are always identical so we can just pick the first one.
This will get cleaned up once T11823 is fixed properly.
