unable to commit to particular branch in shared repository

$ bzr init-repo planet-ubuntu
$ cd planet-ubuntu
$ bzr checkout lp:~planet-ubuntu/config/main planet-ubuntu
$ # << make changes >>
$ bzr commit -m "foo"
Committing to: bzr+ssh://bazaar.launchpad.net/~planet-ubuntu/config/main/
modified config.ini
added heads/jodh.png
Doing on-the-fly conversion from RepositoryFormat2a() to RemoteRepositoryFormat(_network_name='Bazaar pack repository format 1 (needs bzr 0.92)\n').
This may take some time. Upgrade the repositories to the same format for better performance.
bzr: ERROR: RemoteRepository(bzr+ssh://bazaar.launchpad.net/~planet-ubuntu/config/main/.bzr/)
is not compatible with
CHKInventoryRepository('file:///data/bzr/planet-ubuntu/.bzr/repository/')
different rich-root support
$ cd /tmp
$ bzr checkout lp:~planet-ubuntu/config/main planet-ubuntu
$ cd planet-ubuntu
$ # << make changes >>
$ bzr commit -m "foo"
bzr 2.5.0 is too new for pipeline 1.1.0
Committing to: /tmp/planet-ubuntu/
modified config.ini
added heads/jodh.png
Committed revision 1532.
$

So, the commit only works when not using a shared repository, but why?

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: bzr 2.5.0-2ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic-pae 3.2.14
Uname: Linux 3.2.0-24-generic-pae i686
ApportVersion: 2.0.1-0ubuntu7
Architecture: i386
Date: Wed May 16 17:20:33 2012
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, user)
 LANG=fr_CA.UTF8
 SHELL=/bin/bash
SourcePackage: bzr
UpgradeStatus: Upgraded to precise on 2012-01-12 (125 days ago)