turns out pull was only updating the current branch's remote ref — git pull <remote> <branch> with an explicit refspec skips the remote's normal fetch = +refs/heads/* config, so other origin/* refs went stale until you separately ran git fetch. that's why new origin branches sometimes weren't there after a pull.

• run an explicit git fetch --prune before the rebase-pull so all remote-tracking branches refresh
• drop the backgrounded git remote prune — --prune on the fetch handles it synchronously
• scoped to $remote (not --all) to preserve behavior for repos with multiple remotes

to test:

• in a repo where origin has a brand-new branch you don't have locally, run ./pull and confirm git branch -r now shows it
• delete a branch on origin, run ./pull, confirm the stale origin/* ref is gone