The call to compute_sheet will (indirectly) create an hr.payslip.line
that whose name is translatable. This means an ir.translation record
will be created.

If an applicant visit the salary page with his browser in a language not
activated, the context will contain this language and a translation
will be created (and crash)
```
Error:
Odoo Server Error

Traceback (most recent call last):
  File "/home/odoo/src/odoo/13.0/odoo/http.py", line 624, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/home/odoo/src/odoo/13.0/odoo/http.py", line 310, in _handle_exception
    raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
  File "/home/odoo/src/odoo/13.0/odoo/tools/pycompat.py", line 14, in reraise
    raise value
  File "/home/odoo/src/odoo/13.0/odoo/http.py", line 669, in dispatch
    result = self._call_function(**self.params)
  File "/home/odoo/src/odoo/13.0/odoo/http.py", line 350, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/home/odoo/src/odoo/13.0/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/home/odoo/src/odoo/13.0/odoo/http.py", line 339, in checked_call
    result = self.endpoint(*a, **kw)
  File "/home/odoo/src/odoo/13.0/odoo/http.py", line 915, in __call__
    return self.method(*args, **kw)
  File "/home/odoo/src/odoo/13.0/odoo/http.py", line 515, in response_wrap
    response = f(*args, **kw)
  File "/home/odoo/src/enterprise/13.0/hr_contract_salary/controllers/main.py", line 424, in compute_net
    payslip.with_context(salary_simulation=True).compute_sheet()
  File "/home/odoo/src/enterprise/13.0/hr_payroll/models/hr_payslip.py", line 166, in compute_sheet
    payslip.write({'line_ids': lines, 'number': number, 'state': 'verify', 'compute_date': fields.Date.today()})
  File "/home/odoo/src/odoo/13.0/addons/mail/models/mail_thread.py", line 322, in write
    result = super(MailThread, self).write(values)
  File "/home/odoo/src/odoo/13.0/addons/mail/models/mail_activity.py", line 715, in write
    return super(MailActivityMixin, self).write(vals)
  File "/home/odoo/src/odoo/13.0/odoo/models.py", line 3542, in write
    field.write(self, vals[fname])
  File "/home/odoo/src/odoo/13.0/odoo/fields.py", line 2823, in write
    return self.write_batch([(records, value)])
  File "/home/odoo/src/odoo/13.0/odoo/fields.py", line 2844, in write_batch
    return self.write_real(records_commands_list, create)
  File "/home/odoo/src/odoo/13.0/odoo/fields.py", line 3008, in write_real
    flush()
  File "/home/odoo/src/odoo/13.0/odoo/fields.py", line 2972, in flush
    comodel.create(to_create)
  File "<decorator-gen-224>", line 2, in create
  File "/home/odoo/src/odoo/13.0/odoo/api.py", line 336, in _model_create_multi
    return create(self, arg)
  File "/home/odoo/src/enterprise/13.0/hr_payroll/models/hr_payslip.py", line 393, in create
    return super(HrPayslipLine, self).create(vals_list)
  File "<decorator-gen-3>", line 2, in create
  File "/home/odoo/src/odoo/13.0/odoo/api.py", line 336, in _model_create_multi
    return create(self, arg)
  File "/home/odoo/src/odoo/13.0/odoo/models.py", line 3742, in create
    records = self._create(data_list)
  File "/home/odoo/src/odoo/13.0/odoo/models.py", line 3907, in _create
    Translations._set_ids(tname, 'model', self.env.lang, record.ids, val, val)
  File "/home/odoo/src/odoo/13.0/odoo/addons/base/models/ir_translation.py", line 279, in _set_ids
    for res_id in set(ids) - set(existing_ids)
  File "<decorator-gen-47>", line 2, in create
  File "/home/odoo/src/odoo/13.0/odoo/api.py", line 336, in _model_create_multi
    return create(self, arg)
  File "/home/odoo/src/odoo/13.0/odoo/addons/base/models/ir_translation.py", line 554, in create
    records = super(IrTranslation, self.sudo()).create(vals_list).with_env(self.env)
  File "<decorator-gen-3>", line 2, in create
  File "/home/odoo/src/odoo/13.0/odoo/api.py", line 336, in _model_create_multi
    return create(self, arg)
  File "/home/odoo/src/odoo/13.0/odoo/models.py", line 3742, in create
    records = self._create(data_list)
  File "/home/odoo/src/odoo/13.0/odoo/models.py", line 3859, in _create
    cache_value = field.convert_to_cache(value, record)
  File "/home/odoo/src/odoo/13.0/odoo/fields.py", line 2223, in convert_to_cache
    raise ValueError("Wrong value for %s: %r" % (self, value))
ValueError: Wrong value for ir.translation.lang: 'nl_BE'
```
This patch hides the error by dropping the visitor language

@rco-odoo this patch just hides the problem by dropping the language in the context but is a fix in the ORM worth it? For instance something like odoo-dev/odoo@c0a15be5aca96cccbaa06186ff90ec2bdce7e919 fixes the issue as well but is definitly more risky.
I am also surprised we don't get this kind of issue more often with the website.

Forward-Port-Of: odoo/enterprise#10264
Forward-Port-Of: odoo/enterprise#10231