Queue for plan stages with one agent is not FIFO

In the situation where there is only one agent (which matches all capabilities and requirements of all plans), Bamboo will randomly pick a stage from all currently queued plans to run. For example,

1. Plan A: Stage 1
2. Plan B: Stage 1
3. Plan B: Stage 2
4. Plan A: Stage 2
5. Plan A: Stage 3

This is unintuitive behaviour. Bamboo should commit to FIFO ordering for plan stages in this situation.