Test if contextual company id is positive before using it

Closes #13176
(grafted from fa023763f7b00cd4fbfa9e818bf25db9e259cfbd)

--HG--
branch : 7.0

modules/account/party.py

@@ -111,7 +111,7 @@ class Party(CompanyMultiValueMixin, metaclass=PoolMeta):
         pool = Pool()
         Company = pool.get('company.company')
         company_id = Transaction().context.get('company')
-        if company_id:
+        if company_id >= 0:
             company = Company(company_id)
             return company.currency.id