reentry map: --group filter also returns empty groups

[ltalirz]

See e.g.

reentry map --group aiida.data
{'Babel': {},
 'Jinja2': {},
 'Mako': {},
 'aiida-core': {'aiida.data': {'array': reentry.EntryPoint.parse(array = aiida.orm.nodes.data.array.array:ArrayData),
                               'array.bands': reentry.EntryPoint.parse(array.bands = aiida.orm.nodes.data.array.bands:BandsData),
                               'array.kpoints': reentry.EntryPoint.parse(array.kpoints = aiida.orm.nodes.data.array.kpoints:KpointsData),
                               'array.projection': reentry.EntryPoint.parse(array.projection = aiida.orm.nodes.data.array.projection:ProjectionData),
                               'array.trajectory': reentry.EntryPoint.parse(array.trajectory = aiida.orm.nodes.data.array.trajectory:TrajectoryData),
                               'array.xy': reentry.EntryPoint.parse(array.xy = aiida.orm.nodes.data.array.xy:XyData),
                               'base': reentry.EntryPoint.parse(base = aiida.orm.nodes.data:BaseType),
                               'bool': reentry.EntryPoint.parse(bool = aiida.orm.nodes.data.bool:Bool),
                               'cif': reentry.EntryPoint.parse(cif = aiida.orm.nodes.data.cif:CifData),
                               'code': reentry.EntryPoint.parse(code = aiida.orm.nodes.data.code:Code),
                               'dict': reentry.EntryPoint.parse(dict = aiida.orm.nodes.data.dict:Dict),
                               'float': reentry.EntryPoint.parse(float = aiida.orm.nodes.data.float:Float),
                               'folder': reentry.EntryPoint.parse(folder = aiida.orm.nodes.data.folder:FolderData),
                               'int': reentry.EntryPoint.parse(int = aiida.orm.nodes.data.int:Int),
                               'list': reentry.EntryPoint.parse(list = aiida.orm.nodes.data.list:List),
                               'numeric': reentry.EntryPoint.parse(numeric = aiida.orm.nodes.data.numeric:NumericType),
                               'orbital': reentry.EntryPoint.parse(orbital = aiida.orm.nodes.data.orbital:OrbitalData),
                               'remote': reentry.EntryPoint.parse(remote = aiida.orm.nodes.data.remote:RemoteData),
                               'singlefile': reentry.EntryPoint.parse(singlefile = aiida.orm.nodes.data.singlefile:SinglefileData),
                               'str': reentry.EntryPoint.parse(str = aiida.orm.nodes.data.str:Str),
                               'structure': reentry.EntryPoint.parse(structure = aiida.orm.nodes.data.structure:StructureData),
                               'upf': reentry.EntryPoint.parse(upf = aiida.orm.nodes.data.upf:UpfData)}},
 'aiida-diff': {'aiida.data': {'diff': reentry.EntryPoint.parse(diff = aiida_diff.data:DiffParameters)}},
 'alabaster': {},
 'ipython': {},
 'isort': {},
 'mccabe': {},
 'nbconvert': {},
 'pep8-naming': {},
 'pytest-cov': {},
 'reentry': {},
 'sphinx-rtd-theme': {}}