deque mutated during iteration

[oliverbienert]

Hi,

we use flask-principal in a small application with blueprints. Authentication has its own blueprint. Apparently at random we have errors like the one below. Did you know that behavior? Here I read that I may get around that problem by creating a list and 'freeze' the deque. Should I give it a try?

  File
"/opt/venvs/geocalc-login/lib/python3.4/site-packages/flask_principal.py"
, line 479, in _on_before_request
    self.set_identity(identity)
  File
"/opt/venvs/geocalc-login/lib/python3.4/site-packages/flask_principal.py"
, line 419, in set_identity
    for saver in self.identity_savers:
RuntimeError: deque mutated during iteration