* Fix: always use origin/master instead of master for homebrew
**Summary**
Fixes#3415. The old homebrew update script updated the repo
from remote but did not update the local `master` branch, thus
had the potential for conflicts and mismatches. This patch
forces it to use `origin/master` instead and uses the latest
up-to-date version from the source.
**Test plan**
N/A
* Stay on master