Running 'bzr -log -r branch:../other_branch' raises ReadOnlyError

Using latest bzr1.1, the following command:
  bzr log -rbranch:../code_cleanup
caused the following error and traceback:
------------------------------------------------------------------------------------------
bzr: ERROR: bzrlib.errors.ReadOnlyError: A write attempt was made in a read only transaction on KnitPackRepository('file:///home/vincent/dev/.bzr/repository/')

Traceback (most recent call last):
  File "/opt/python/local_modules/bzr-1.1/bzrlib/commands.py", line 806, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/opt/python/local_modules/bzr-1.1/bzrlib/commands.py", line 762, in run_bzr
    ret = run(*run_argv)
  File "/local/python/local_modules/bzr-1.1/bzrlib/commands.py", line 492, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/opt/python/local_modules/bzr-1.1/bzrlib/commands.py", line 772, in ignore_pipe
    result = func(*args, **kwargs)
  File "/opt/python/local_modules/bzr-1.1/bzrlib/builtins.py", line 1713, in run
    rev1 = rev2 = revision[0].in_history(b)
  File "/opt/python/local_modules/bzr-1.1/bzrlib/revisionspec.py", line 225, in in_history
    return self._match_on_and_check(branch, revs)
  File "/opt/python/local_modules/bzr-1.1/bzrlib/revisionspec.py", line 207, in _match_on_and_check
    info = self._match_on(branch, revs)
  File "/opt/python/local_modules/bzr-1.1/bzrlib/revisionspec.py", line 689, in _match_on
    branch.fetch(other_branch, revision_b)
  File "/opt/python/local_modules/bzr-1.1/bzrlib/decorators.py", line 163, in write_locked
    self.lock_write()
  File "/opt/python/local_modules/bzr-1.1/bzrlib/branch.py", line 1345, in lock_write
    repo_token = self.repository.lock_write()
  File "/opt/python/local_modules/bzr-1.1/bzrlib/repofmt/pack_repo.py", line 1964, in lock_write
    raise errors.ReadOnlyError(self)
ReadOnlyError: A write attempt was made in a read only transaction on KnitPackRepository('file:///home/vincent/dev/.bzr/repository/')

bzr 1.1.0 on python 2.5.0.final.0 (sunos5)
arguments: ['/opt/python/local_modules/bzr-1.1/bzr', 'log', '--line', '-rbranch:../code_cleanup']
encoding: '646', fsenc: '646', lang: None
plugins:
  launchpad /opt/python/local_modules/bzr-1.1/bzrlib/plugins/launchpad [unknown]
  multiparent /opt/python/local_modules/bzr-1.1/bzrlib/plugins/multiparent.py [unknown]
*** Bazaar has encountered an internal error.
    Please report a bug at https://bugs.launchpad.net/bzr/+filebug
    including this traceback, and a description of what you
    were doing when the error occurred.
------------------------------------------------------------------------------------------

I am not sure what I was expecting from running this command, but anyway, it fails.
I wondered if it might be related to bug #144300 (https://bugs.launchpad.net/bzr/+bug/144300), but the error message differs a bit.