Clear invoiced progress when copying works

issue11545
review423331004
(grafted from cf92953d5ad93874e7d7e1e3d0a577cddfffe275)

--HG--
branch : 6.0

project.py

@@ -205,6 +205,15 @@ class Progress:
             origins.append(invoiced_progress)
         return origins
 
+    @classmethod
+    def copy(cls, records, default=None):
+        if default is None:
+            default = {}
+        else:
+            default = default.copy()
+        default.setdefault('invoiced_progress', None)
+        return super().copy(records, default=default)
+
 
 class Timesheet: