Greg - FWIW - I interpret the branch names more along the lines of:
* master - what likely will be in the 'next' release with some certainty
* development - what future releases are being developed from, which might be more/less/different than 'master'
Thankfully, weewx doesn't use the full-blown github workflow with 'release' and feature branches and the like. Those can get crazy complicated mechanically.
You probably will see changes made to 'master' that didn't flow through 'development' first, meaning a back-merge master=>development happens occasionally, which would never happen in a strict gitflow process. It's unfortunately pretty easy in the github interface to do a PR that merges to the wrong destination tree (ie, to master, when I should have done the PR toward development). I know I mess that up too frequently.