Mutually Exclusive Labels
Description
When reading #17186 (closed) I thought everyone else already use labels for some state-like control (including myself).
Flow stages like "Development", "Testing", "Staging" might be commonly used.
But in order to achieve consistent state-like flows one issue could rarely be in more than one state (fill free to spot me wrong).
Proposal
I propose the adding of a flag to mark some labels as State Labels (or any other name). Thus marked labels should not appear together in issues.
Suppose I have a issue which is under active development so I would have labeled it with State Label "Development".
After some days of hard work I would say "Hmm. I think it is ready." and once I push it, I would move it to the next phase possibly labeling it "Testing". Here the magic would be seen. As "Development" and "Testing" are both State Labels, the later would replace the former.
Therefore, only one State Label is allowed per issue.
Thoughts?