title: python yaml error on odoo11 stock module installation. yaml.constructor.ConstructorError: could not determine a constructor for the tag '!python'
body: <p>I have setup a <code>odoo11</code> database and trying to install stock module but it will generate python yaml error. </p>
  
  <p>Error logs: </p>
  
  <pre><code>2019-04-09 12:21:06,147 15820 INFO sicpa_db odoo.modules.loading: loading stock/views/stock_template.xml
  2019-04-09 12:21:06,391 15820 INFO sicpa_db odoo.modules.loading: loading stock/views/procurement_views.xml
  2019-04-09 12:21:06,546 15820 INFO sicpa_db odoo.modules.loading: loading stock/data/default_barcode_patterns.xml
  2019-04-09 12:21:06,592 15820 INFO sicpa_db odoo.modules.loading: loading stock/data/stock_data.xml
  2019-04-09 12:21:07,294 15820 INFO sicpa_db odoo.modules.loading: loading stock/data/stock_data.yml
  2019-04-09 12:21:07,300 15820 WARNING sicpa_db odoo.modules.loading: Transient module states were reset
  2019-04-09 12:21:07,336 15820 ERROR sicpa_db odoo.modules.registry: Failed to load registry
  Traceback (most recent call last):
    File "/home/gajanan/others/erp/odoo11-git/odoo/modules/registry.py", line 85, in new
      odoo.modules.load_modules(registry._db, force_demo, status, update_module)
    File "/home/gajanan/others/erp/odoo11-git/odoo/modules/loading.py", line 380, in load_modules
      loaded_modules, update_module, models_to_check)
    File "/home/gajanan/others/erp/odoo11-git/odoo/modules/loading.py", line 274, in load_marked_modules
      perform_checks=perform_checks, models_to_check=models_to_check
    File "/home/gajanan/others/erp/odoo11-git/odoo/modules/loading.py", line 181, in load_module_graph
      _load_data(cr, module_name, idref, mode, kind='data')
    File "/home/gajanan/others/erp/odoo11-git/odoo/modules/loading.py", line 95, in _load_data
      tools.convert_file(cr, module_name, filename, idref, mode, noupdate, kind, report)
    File "/home/gajanan/others/erp/odoo11-git/odoo/tools/convert.py", line 789, in convert_file
      convert_yaml_import(cr, module, fp, kind, idref, mode, noupdate, report)
    File "/home/gajanan/others/erp/odoo11-git/odoo/tools/yaml_import.py", line 854, in yaml_import
      yaml_interpreter.process(yaml_string)
    File "/home/gajanan/others/erp/odoo11-git/odoo/tools/yaml_import.py", line 794, in process
      for node in yaml.load(yaml_string):
    File "/home/gajanan/.local/lib/python3.5/site-packages/yaml/__init__.py", line 114, in load
    File "/home/gajanan/.local/lib/python3.5/site-packages/yaml/constructor.py", line 43, in get_single_data
    File "/home/gajanan/.local/lib/python3.5/site-packages/yaml/constructor.py", line 52, in construct_document
    File "/home/gajanan/.local/lib/python3.5/site-packages/yaml/constructor.py", line 404, in construct_yaml_map
    File "/home/gajanan/.local/lib/python3.5/site-packages/yaml/constructor.py", line 210, in construct_mapping
    File "/home/gajanan/.local/lib/python3.5/site-packages/yaml/constructor.py", line 131, in construct_mapping
    File "/home/gajanan/.local/lib/python3.5/site-packages/yaml/constructor.py", line 92, in construct_object
    File "/home/gajanan/.local/lib/python3.5/site-packages/yaml/constructor.py", line 420, in construct_undefined
  yaml.constructor.ConstructorError: could not determine a constructor for the tag '!python'
    in "&lt;byte string&gt;", line 2, column 3:
        !python {model: ir.model.data, i ... 
        ^
  </code></pre>
  
  <p>I am unable to install other apps too, please help.</p>