Pass transition only when possible.

More then one builder can be called in same time for same invoice.

master/bt5/vifib_base/SkinTemplateItem/portal_skins/vifib_simulation/VifibInvoiceTransaction_postGeneration.xml

@@ -74,7 +74,8 @@ if invoice.getSimulationState() == \'draft\':\n
   invoice.plan(comment=translateString(\'Initialised by Delivery Builder.\'), activate_kw={\'tag\': tag})\n
 \n
 # Update causality workflow\n
-invoice.startBuilding()\n
+if invoice.getPortalObject().portal_workflow.isTransitionPossible(invoice, \'start_building\'):\n
+  invoice.startBuilding()\n
 invoice.updateCausalityState()\n
 \n
 # update specialise from movements\n

master/bt5/vifib_base/bt/revision

-414
\ No newline at end of file
+415
\ No newline at end of file