text: Title: Kinto returns HTTP 500 on get_records endpoint (unbalanced parenthesis)
  Body: **Steps to reproduce**
  _docker run -p 8888:8888 kinto/kinto-server_
  Running kinto 14.0.1.dev0.
  
  Request
  ```
  GET /v1/buckets/)EFg9=)%5E(M~%2037/collections/M*D;1Z/records HTTP/1.1
  Host: 127.0.0.1:8888
  ```
  Response
  ```
  {
      "code": 500,
      "errno": 999,
      "error": "Internal Server Error",
      "message": "A programmatic error occured, developers have been informed.",
      "info": "https://github.com/Kinto/kinto/issues/"
  }
  ```
  
  Log:
  ```
  "GET /v1/buckets/)EFg9=)%5E(M~%2037/collections/M*D;1Z/records?" ? (? ms) unbalanced parenthesis at position 10 errno=999
  Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/pyramid/tweens.py", line 41, in excview_tween
  response = handler(request)
  File "/app/kinto/core/events.py", line 157, in tween
  File "/usr/local/lib/python3.7/site-packages/pyramid/router.py", line 148, in handle_request
  registry, request, context, context_iface, view_name
  File "/usr/local/lib/python3.7/site-packages/pyramid/view.py", line 683, in _call_view
  response = view_callable(context, request)
  File "/usr/local/lib/python3.7/site-packages/pyramid/config/views.py", line 169, in __call__
  return view(context, request)
  File "/usr/local/lib/python3.7/site-packages/pyramid/config/views.py", line 188, in attr_view
  File "/usr/local/lib/python3.7/site-packages/pyramid/config/views.py", line 214, in predicate_wrapper
  
  File "/usr/local/lib/python3.7/site-packages/pyramid/viewderivers.py", line 323, in secured_view
  
  result = permitted(context, request)
  File "/usr/local/lib/python3.7/site-packages/pyramid/viewderivers.py", line 320, in permitted
  return authz_policy.permits(context, principals, permission)
  File "/app/kinto/core/authorization.py", line 94, in permits
  context.fetch_shared_objects(permission, principals, self.get_bound_permissions)
  File "/app/kinto/core/authorization.py", line 229, in fetch_shared_objects
  by_obj_id = self._get_accessible_objects(principals, bound_perms, with_children=False)
  File "/app/kinto/core/decorators.py", line 45, in decorated
  re.error: unbalanced parenthesis at position 10
  "GET /v1/buckets/)EFg9=)%5E(M~%2037/collections/M*D;1Z/records?" 500 (5 ms) agent=Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36 errno=999 lang=en-US,en;q=0.9 time=2020-12-14T13:18:58.482000
  ```