I had the same issue with my branch, the problem is known in Launchpad.
To fix it, you not only have to fix branch.conf as you already
guessed, but also trigger a re-reading of the file. This can be done
with a simple python script that you can find in the bug report.
To access the file branch.conf, you can use sftp, e.g.
sftp> get branch.conf
[edit the branch.conf file]
sftp> put branch.conf
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