Inside oneof_schema not work default values for nested keys

[zygfrydos]

oneof_schema in my case is for future use, to add new compression program, but now its only for 7zip. One of compression program must be set
Code:

YAML_SCHEMA={    
    'compression':{
        'type':'dict',
        'required':True,
        'oneof_schema':[
            {
                '7z':{
                    'type':'dict',
                    'required':True,
                    'schema':{
                        'cmd_path':{'type':'string', 'required':True},
                        'passwd':{'type':'string'},
                        'compress_level':{'type': 'string', 'default':5, 'coerce': int},
                        'attr':{
                            'type':'list',
                            'contains':'y', # must cotain don't ask else will be hang
                            'default':['mmt',   # enable multithreading
                                       'ms',    # solid archive (without appending files in feature)
                                       'y',     # don't ask, auto yes
                                       'mhe=on',# hide file name in archive
                                       ]},
                        'exlude_attr':{
                            'type':'list',
                            'default':['r!$RECYCLE.BIN',                # windows recycle.bin
                                       '!System*Volume*Information',    # some other fat garbage
                                       'r!*.mdf',                       # except database file from mssql
                                       'r!*.ldf',                       # except log file from mssql
                                       '!.__sync__*'                   # except sync file from owncloud
                                       ]
                            }
                        }
                    },
            },]
        }
    }
    import yaml
    from cerberus import Validator
    v = Validator(YAML_SCHEMA)
    doc={'compression':{
        '7z':{
            'cmd_path':'somewhere'
            }}}
    print(yaml.dump(v.normalized(doc), Dumper=yaml.Dumper))

Give me out:

compression:
  7z:
    cmd_path: somewhere

When I change schema to:

YAML_SCHEMA={    
    'compression':{
        'type':'dict',
        'required':True,
        'schema':{
            '7z':{
                'type':'dict',
                'required':True,
                'schema':{
                    'cmd_path':{'type':'string', 'required':True},
                    'passwd':{'type':'string'},
                    'compress_level':{'type': 'string', 'default':5, 'coerce': int},
                    'attr':{
                        'type':'list',
                        'contains':'y', # must cotain don't ask else will be hang
                        'default':['mmt',   # enable multithreading
                                   'ms',    # solid archive (without appending files in feature)
                                   'y',     # don't ask, auto yes
                                   'mhe=on',# hide file name in archive
                                   ]},
                    'exlude_attr':{
                        'type':'list',
                        'default':['r!$RECYCLE.BIN',                # windows recycle.bin
                                   '!System*Volume*Information',    # some other fat garbage
                                   'r!*.mdf',                       # except database file from mssql
                                   'r!*.ldf',                       # except log file from mssql
                                   '!.__sync__*'                   # except sync file from owncloud
                                   ]
                        }
                    }
                },
            }
        }
    }

Output is correct:

compression:
  7z:
    attr:
    - mmt
    - ms
    - y
    - mhe=on
    cmd_path: somewhere
    compress_level: 5
    exlude_attr:
    - r!$RECYCLE.BIN
    - '!System*Volume*Information'
    - r!*.mdf
    - r!*.ldf
    - '!.__sync__*'