exceptions.ValueError on badly formated colocated branch name

[Elron A. Yellin]

$ bzr rmbranch file:,colo-branch-name
instead of
$ bzr rmbranch file:,branch=colo-branch-name
yields

bzr: ERROR: exceptions.ValueError: need more than 1 value to unpack

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 930, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 1141, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 673, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 697, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/builtins.py", line 6486, in run
    br = open_nearby_branch(near=directory, location=location)
  File "/usr/lib/python2.7/dist-packages/bzrlib/builtins.py", line 182, in open_nearby_branch
    possible_transports=possible_transports)
  File "/usr/lib/python2.7/dist-packages/bzrlib/branch.py", line 185, in open
    possible_transports=possible_transports, _unsupported=_unsupported)
  File "/usr/lib/python2.7/dist-packages/bzrlib/controldir.py", line 687, in open
    t = _mod_transport.get_transport(base, possible_transports)
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/__init__.py", line 1680, in get_transport
    return get_transport_from_url(location_to_url(base), possible_transports)
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/__init__.py", line 1655, in get_transport_from_url
    transport, last_err = _try_transport_factories(url, factory_list)
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/__init__.py", line 1687, in _try_transport_factories
    return factory.get_obj()(base), None
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/local.py", line 67, in __init__
    super(LocalTransport, self).__init__(base)
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/__init__.py", line 331, in __init__
    urlutils.split_segment_parameters(base))
  File "/usr/lib/python2.7/dist-packages/bzrlib/urlutils.py", line 539, in split_segment_parameters
    (key, value) = subsegment.split("=", 1)
ValueError: need more than 1 value to unpack

bzr 2.6b2 on python 2.7.3 (Linux-3.5.0-17-generic-x86_64-with-
    Ubuntu-12.10-quantal)
arguments: ['/usr/bin/bzr', 'rmbranch', 'file:,MixMatrixRefactor']
plugins: bash_completion[2.6b2], bzrtools[2.5.0], changelog_merge[2.6b2],
    explorer[1.3.0], fastimport[0.13.0], grep[0.5.0dev], launchpad[2.6b2],
    loggerhead[1.18.1], netrc_credential_store[2.6b2], news_merge[2.6b2],
    po_merge[2.6b2], qbzr[0.22.2], search[1.7.0dev], stats[0.2.0dev],
    weave_fmt[2.6b2], xmloutput[0.8.8]
encoding: 'utf-8', fsenc: 'UTF-8', lang: 'en_US.UTF-8'