Prevent StringPartitioned to evaluate its argument on instanciation [CUSTOM]

[nicoe]

PCLAS-540

[CoopVincent]

Hello,

Le fix fait crash l'update du serveur:

Traceback (most recent call last):
  File "/home/vincent.garde/Dev/venvs/coog/bin/trytond-admin", line 36, in <module>
    admin.run(options)
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/admin.py", line 150, in run
    pool = _init_pool(db_name, options, lang)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/admin.py", line 91, in _init_pool
    pool.init(
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/pool.py", line 209, in init
    restart = not load_modules(
                  ^^^^^^^^^^^^^
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/modules/__init__.py", line 599, in load_modules
    _load_modules(update)
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/modules/__init__.py", line 562, in _load_modules
    load_module_graph(graph, pool, update, lang, options)
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/modules/__init__.py", line 236, in load_module_graph
    pool.setup(classes)
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/pool.py", line 306, in setup
    cls.__post_setup__()
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/modules/coog_core/model.py", line 2159, in __post_setup__
    field_copy(Model, fname, cls)
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/modules/coog_core/model.py", line 2147, in field_copy
    raise e
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/modules/coog_core/model.py", line 2144, in field_copy
    copy = field.__class__(string=field.string, readonly=True)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/vincent.garde/Dev/coog-master/tryton/trytond/trytond/model/fields/field.py", line 289, in __init__
    assert string, 'a string is required'
AssertionError: a string is required

Le modèle incriminé est TreatIjPeriodSelectLine, qui hérite de view_only , et l'erreur se joue sur le champ create_date (donc la string est renseignée en lazy_gettext).

[CoopVincent]

LGTM avec ce commit, j'ai ma lazy_gettext bien chargée dans l'appli. et le wizard de traduction réagit correctement, GJ