#TIL when you contribute to a project that use #Appveyor CI to test build on #Windows, the system sometimes build the code you have just pushed, but often a previous version of the code (in spite of what the commit hash say).
It can therefore be convenient to output canaries in the build script so that you can ensure success / failures are related to the last version of the code (by checking them visually in the log).
When it does not match:
git commit --amend
git push -f