extending python-neutronclient commands with an external module fails

The framework to extend python-neutronclient with commands provided by an external module has merged with the change-id : I5b2fe530c90b5ce1243fc10341d6d434a1ecea7a

So in an external module I've added an entry_point in my setup.cfg :

[entry_points]
neutronclient.extension=
    my_ext = my_module

my_module is a python file containing classes which extend NeutronClientExtension and ClientExtensionList :

...

class myExt(extension.NeutronClientExtension):
    resource = 'my_ext'
    resource_plural = '%ss' % resource
    object_path = '/%s' % resource_plural
    resource_path = '/%s/%%s' % resource_plural
    versions = ['2.0']

class myExtList(extension.ClientExtensionList,
                           myExt):
    shell_command = 'my-ext-list'
    list_columns = ['id']
    pagination_support = True
    sorting_support = True

When I try to use the command :

#neutron my-ext-list

It fails with the error "unknown command"

After using a debugger, I can see that my module is correctly loaded, the command is correctly registered in the command manager of cliff, but it isn't registered in the command dict of the NeutronShell class