When decky is uncertain of branch, set the setting to match the guess (#480)

* If branch setting is missing, set it using the 'guess' from backend

* Make the frontend default to stable branch like the backend

backend/updater.py

@@ -67,9 +67,11 @@ class Updater:
             logger.info("Current branch is not set, determining branch from version...")
             if self.localVer.startswith("v") and "-pre" in self.localVer:
                 logger.info("Current version determined to be pre-release")
+                manager.setSetting('branch', 1)
                 return 1
             else:
                 logger.info("Current version determined to be stable")
+                manager.setSetting('branch', 0)
                 return 0
         return ver
 

frontend/src/components/settings/pages/general/BranchSelect.tsx

@@ -21,7 +21,7 @@ const BranchSelect: FunctionComponent<{}> = () => {
     t('BranchSelect.update_channel.prerelease'),
     t('BranchSelect.update_channel.testing'),
   ];
-  const [selectedBranch, setSelectedBranch] = useSetting<UpdateBranch>('branch', UpdateBranch.Prerelease);
+  const [selectedBranch, setSelectedBranch] = useSetting<UpdateBranch>('branch', UpdateBranch.Stable);
 
   return (
     // Returns numerical values from 0 to 2 (with current branch setup as of 8/28/22)