This specific error is only an issue when you have the option for checking AUR script updates in Pamac.
It does not matter what your branch is - the aur database is the same.
Avoid the issue all-together by disabling the Pamac AUR check
It is well known that combining the system update with an AUR rebuild may and likely will cause serious headaches. Just search the forum - there is countless issues on this.
Use a helper script like [root tip] [HowTo] Check if your AUR build scripts have been updated