Clear employee fields on copy

issue10209
review357511002

purchase_request.py

@@ -332,6 +332,15 @@ class PurchaseRequest(ModelSQL, ModelView):
                         request=request.rec_name))
         super(PurchaseRequest, cls).delete(requests)
 
+    @classmethod
+    def copy(cls, requests, default=None):
+        if default is None:
+            default = {}
+        else:
+            default = default.copy()
+        default.setdefault('purchased_by')
+        return super().copy(requests, default=default)
+
     @classmethod
     def find_best_product_supplier(cls, product, date, **pattern):
         "Return the best product supplier to request product at date"