It is currently very easy to shoot yourself in the foot by running something like

fedpkg chain-build --target f39-build-side-12345

while accidentally still being in a checkout of the f40 branch.

This will work, but will not do what's intended - it will build the contents of the f40 branch against the f39 side-tag.

It would be great if fedpkg bailed and printed an error if target and dist-git branch mismatched (possibly with an escape hatch for when you know what you're doing).