> For context, only a single major version of a package is allowed to exist in a version set at a time.
This is not entirely true. A version set can have an arbitrary number of major versions of the same package. This is convenient if you have multiple applications feeding from the same upstream version set. You can add a new major version to the upstream version set and the applications can all switch over independently. This is of course how different applications can all consume from the "live" VS which has multiple major versions of many packages.
What you can't have is multiple major versions of the same package in the runtime closure of your application. It's fine to have multiple versions of build and test tools, but you can't deploy multiple versions of the same package via a VFI, which includes just the runtime closure. (You also can't have multiple packages providing the same file at the same path, but it is surprising how uncommon that is when you think about it).
Ah right I misspoke. I was conflating it with the common case, which is that one of the deps for versionset's target was changed. I agree with your other comment, the first year or so I just cargo culted Brazil and versionset changes until I actually had to fix more complicated build issues (e.g. Packaging up a third party lib)
This is not entirely true. A version set can have an arbitrary number of major versions of the same package. This is convenient if you have multiple applications feeding from the same upstream version set. You can add a new major version to the upstream version set and the applications can all switch over independently. This is of course how different applications can all consume from the "live" VS which has multiple major versions of many packages.
What you can't have is multiple major versions of the same package in the runtime closure of your application. It's fine to have multiple versions of build and test tools, but you can't deploy multiple versions of the same package via a VFI, which includes just the runtime closure. (You also can't have multiple packages providing the same file at the same path, but it is surprising how uncommon that is when you think about it).