Price currency is already set on Open Sale Order.

So there is no need to require it on line.

master/bt5/vifib_erp5/PropertySheetTemplateItem/portal_property_sheets/VifibOpenSaleOrderLineConstraint/price_currency_constraint.xml

-<?xml version="1.0"?>
-<ZopeData>
-  <record id="1" aka="AAAAAAAAAAE=">
-    <pickle>
-      <global name="Category Membership Arity Constraint" module="erp5.portal_type"/>
-    </pickle>
-    <pickle>
-      <dictionary>
-        <item>
-            <key> <string>_identity_criterion</string> </key>
-            <value>
-              <persistent> <string encoding="base64">AAAAAAAAAAI=</string> </persistent>
-            </value>
-        </item>
-        <item>
-            <key> <string>_range_criterion</string> </key>
-            <value>
-              <persistent> <string encoding="base64">AAAAAAAAAAM=</string> </persistent>
-            </value>
-        </item>
-        <item>
-            <key> <string>constraint_base_category</string> </key>
-            <value>
-              <tuple>
-                <string>price_currency</string>
-              </tuple>
-            </value>
-        </item>
-        <item>
-            <key> <string>constraint_portal_type</string> </key>
-            <value> <string>python: (\'Currency\',)</string> </value>
-        </item>
-        <item>
-            <key> <string>description</string> </key>
-            <value>
-              <none/>
-            </value>
-        </item>
-        <item>
-            <key> <string>id</string> </key>
-            <value> <string>price_currency_constraint</string> </value>
-        </item>
-        <item>
-            <key> <string>max_arity</string> </key>
-            <value> <int>1</int> </value>
-        </item>
-        <item>
-            <key> <string>min_arity</string> </key>
-            <value> <int>1</int> </value>
-        </item>
-        <item>
-            <key> <string>portal_type</string> </key>
-            <value> <string>Category Membership Arity Constraint</string> </value>
-        </item>
-        <item>
-            <key> <string>use_acquisition</string> </key>
-            <value> <int>0</int> </value>
-        </item>
-      </dictionary>
-    </pickle>
-  </record>
-  <record id="2" aka="AAAAAAAAAAI=">
-    <pickle>
-      <global name="PersistentMapping" module="Persistence.mapping"/>
-    </pickle>
-    <pickle>
-      <dictionary>
-        <item>
-            <key> <string>data</string> </key>
-            <value>
-              <dictionary/>
-            </value>
-        </item>
-      </dictionary>
-    </pickle>
-  </record>
-  <record id="3" aka="AAAAAAAAAAM=">
-    <pickle>
-      <global name="PersistentMapping" module="Persistence.mapping"/>
-    </pickle>
-    <pickle>
-      <dictionary>
-        <item>
-            <key> <string>data</string> </key>
-            <value>
-              <dictionary/>
-            </value>
-        </item>
-      </dictionary>
-    </pickle>
-  </record>
-</ZopeData>

master/bt5/vifib_erp5/bt/revision

-388
\ No newline at end of file
+389
\ No newline at end of file