erp5_interface_post: improve allow_export's after-actions to be race-condition proof

bt5/erp5_interface_post/SkinTemplateItem/portal_skins/erp5_interface_post/InterfacePost_disallowExportOfSameInterfacePostList.py → bt5/erp5_interface_post/SkinTemplateItem/portal_skins/erp5_interface_post/InterfacePost_disallowExportOfSameInterfacePostListAndExport.py

 from Products.ZSQLCatalog.SQLCatalog import SimpleQuery
 
+# Because this script can be called at the ~ same time on different
+# posts, it can raise race conditions where several posts disallow
+# export of each other, resulting in nothing is exported. Checking
+# the current state of the post here prevents a post which has
+# already been disallowed to disallow the post which disalowed it.
+# 2 Posts can still be exported at same time if one isn't indexed
+# correctly yet.
+if context.getSimulationState() != 'exportable':
+  return
+
+
+# 1/ Disallow export of posts for the same origin message
 portal = context.getPortalObject()
 module = context.getParentValue()
 
@@ -13,3 +25,6 @@ exportable_post_list = portal.portal_catalog(
 
 for exportable_post in exportable_post_list:
   exportable_post.disallowExport()
+
+# 2/ Export post
+context.InterfacePost_exportAfterAllowExport()

bt5/erp5_interface_post/SkinTemplateItem/portal_skins/erp5_interface_post/InterfacePost_disallowExportOfSameInterfacePostList.xml → bt5/erp5_interface_post/SkinTemplateItem/portal_skins/erp5_interface_post/InterfacePost_disallowExportOfSameInterfacePostListAndExport.xml

@@ -54,7 +54,7 @@
         </item>
         <item>
             <key> <string>id</string> </key>
-            <value> <string>InterfacePost_disallowExportOfSameInterfacePostList</string> </value>
+            <value> <string>InterfacePost_disallowExportOfSameInterfacePostListAndExport</string> </value>
         </item>
       </dictionary>
     </pickle>

bt5/erp5_interface_post/WorkflowTemplateItem/portal_workflow/interface_post_workflow/scripts/afterAllowExport.py

 post = state_change['object']
 
-post.activate(tag='interface_post_disallow_export') \
-  .InterfacePost_disallowExportOfSameInterfacePostList()
-
-post.activate(after_tag='interface_post_disallow_export') \
-  .InterfacePost_exportAfterAllowExport()
+# Priority 2 is just enough to be executed after the immediateReindexObject
+post.activate(serialization_tag='export_interface_post',
+              priority=2) \
+  .InterfacePost_disallowExportOfSameInterfacePostListAndExport()