[aur-general] brz pkgver() problem when updating on existing bzr repo

[SanskritFritz]

As I updated the PKGBUILD for he new autobump feature I observed the
following problem on my
https://aur.archlinux.org/packages/anamnesis-bzr package:

When I run makepkg the first time, the bzr repo gets fetched, all ok.
However running makepkg the second time gives the following error:

==> ERROR: /Common/Builds/aur/anamnesis-bzr/anamnesis is not a branch
of bzr://anamnesis.bzr.sourceforge.net/bzrroot/anamnesis

I don't know much about bzr, so I don't know what this error means.
Can you help me please, is this a problem with the bzr url format, or
a bug in makepkg or something else?