cubicweb #3261809 TypeError: 'RQLVocabularyConstraint' object is not iterable [rejected]

on db-restore or upgrade

File "/usr/bin/cubicweb-ctl", line 4, in <module>
  run(sys.argv[1:])
File "/home/arthur/src/public/cubicweb/cubicweb/cwctl.py", line 1061, in run
  CWCTL.run(args)
File "/home/arthur/src/public/cubicweb/logilab/common/clcommands.py", line 134, in run
  sys.exit(command.main_run(args, rcfile))
File "/home/arthur/src/public/cubicweb/logilab/common/clcommands.py", line 263, in main_run
  self.run(args)
File "/home/arthur/src/public/cubicweb/cubicweb/server/serverctl.py", line 878, in run
  format=self.config.format)
File "/home/arthur/src/public/cubicweb/cubicweb/server/serverctl.py", line 742, in _local_restore
  mih.restore_database(backupfile, drop, systemonly, askconfirm=False, format=format)
File "/home/arthur/src/public/cubicweb/cubicweb/server/migractions.py", line 261, in restore_database
  repo.init_cnxset_pool()
File "/home/arthur/src/public/cubicweb/cubicweb/server/repository.py", line 242, in init_cnxset_pool
  self.set_schema(config.load_schema())
File "/home/arthur/src/public/cubicweb/cubicweb/server/serverconfig.py", line 362, in load_schema
  schema = CubicWebSchemaLoader().load(self, **kwargs)
File "/home/arthur/src/public/cubicweb/cubicweb/schema.py", line 1180, in load
  return super(CubicWebSchemaLoader, self).load(config, path=path, **kwargs)
File "/home/arthur/src/public/cubicweb/cubicweb/schema.py", line 1145, in load
  path, config.appid, register_base_types=False, **kwargs)
File "/home/arthur/src/public/cubicweb/yams/reader.py", line 133, in load
  post_build_callbacks=self.post_build_callbacks)
File "/home/arthur/src/public/cubicweb/yams/reader.py", line 79, in fill_schema
  definition = definition()
File "/home/arthur/src/public/cubicweb/yams/buildobjs.py", line 517, in __init__
  self.constraints = list(self.constraints)
prioritynormal
typebug
done in<not specified>
load0.000
load left0.000
closed by<not specified>