Appengine: getCurrentUser() is None but app.yaml login:admin Allows Access?

Today, while working on Google AppEngine code, I discovered a bug in AppEngine, but it just turned out to be a typo. I spent a good few hours googling before tearing things apart and solving the tricky issue. As such, I am sharing my finds to help others’ save some time and stress. Short version is to check your regular expressions in the app.yaml file when adding security to an entire...