Make lines of sales, subscriptions and purchases read only without a company and currency

Closes #13948
(grafted from 47c126ef770e2da3227eaaf10b64398d9b27d6e9)

--HG--
branch : 7.0

modules/purchase/purchase.py

@@ -150,8 +150,14 @@ class Purchase(
             'readonly': ((Eval('state') != 'draft')
                 | (Eval('lines', [0]) & Eval('currency'))),
             })
-    lines = fields.One2Many('purchase.line', 'purchase', 'Lines',
-        states=_states)
+    lines = fields.One2Many(
+        'purchase.line', 'purchase', "Lines",
+        states={
+            'readonly': (
+                (Eval('state') != 'draft')
+                | ~Eval('company')
+                | ~Eval('currency')),
+            })
     comment = fields.Text('Comment')
     untaxed_amount = fields.Function(Monetary(
             "Untaxed", currency='currency', digits='currency'),

modules/sale/sale.py

@@ -177,10 +177,14 @@ class Sale(
             'readonly': ((Eval('state') != 'draft')
                 | (Eval('lines', [0]) & Eval('currency', 0))),
             })
-    lines = fields.One2Many('sale.line', 'sale', 'Lines', states={
-            'readonly': Eval('state') != 'draft',
-            },
-        depends={'party'})
+    lines = fields.One2Many(
+        'sale.line', 'sale', "Lines",
+        states={
+            'readonly': (
+                (Eval('state') != 'draft')
+                | ~Eval('company')
+                | ~Eval('currency')),
+            })
     comment = fields.Text('Comment')
     untaxed_amount = fields.Function(Monetary(
             "Untaxed", digits='currency', currency='currency'), 'get_amount')

modules/sale_subscription/subscription.py

@@ -146,8 +146,11 @@ class Subscription(Workflow, ModelSQL, ModelView):
     lines = fields.One2Many(
         'sale.subscription.line', 'subscription', "Lines",
         states={
-            'readonly': ((Eval('state') != 'draft')
-                | ~Eval('start_date')),
+            'readonly': (
+                (Eval('state') != 'draft')
+                | ~Eval('start_date')
+                | ~Eval('company')
+                | ~Eval('currency')),
             })
 
     quoted_by = employee_field(