Upgrading from 1.10.9 to 1.10.10 gave template error when accessing webserver

[darwinyip]

Apache Airflow version: 1.10.10

Environment:

• Cloud provider or hardware configuration: aws
• OS (e.g. from /etc/os-release): ecs task
• Kernel (e.g. uname -a): python 3.6 image

What happened:

Upgrading from 1.10.9 to 1.10.10 gave error when trying to access UI

Node: 8cec32b7a064
-------------------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/base.py", line 69, in inner
    return self._run_view(f, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/base.py", line 368, in _run_view
    return fn(self, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/flask_login/utils.py", line 258, in decorated_view
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/airflow/utils/db.py", line 74, in wrapper
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/airflow/www/views.py", line 2330, in index
    auto_complete_data=auto_complete_data)
  File "/usr/local/lib/python3.6/site-packages/airflow/www/views.py", line 389, in render
    return super(AirflowViewMixin, self).render(template, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/flask_admin/base.py", line 308, in render
    return render_template(template, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/flask/templating.py", line 140, in render_template
    ctx.app,
  File "/usr/local/lib/python3.6/site-packages/flask/templating.py", line 120, in _render
    rv = template.render(context)
  File "/usr/local/lib/python3.6/site-packages/jinja2/asyncsupport.py", line 76, in render
    return original_render(self, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/jinja2/environment.py", line 1008, in render
    return self.environment.handle_exception(exc_info, True)
  File "/usr/local/lib/python3.6/site-packages/jinja2/environment.py", line 780, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/site-packages/jinja2/_compat.py", line 37, in reraise
    raise value.with_traceback(tb)
  File "/usr/local/lib/python3.6/site-packages/airflow/www/templates/airflow/dags.html", line 20, in top-level template code
    {% extends "airflow/master.html" %}
  File "/usr/local/lib/python3.6/site-packages/airflow/www/templates/airflow/master.html", line 20, in top-level template code
    {% extends "admin/master.html" %}
  File "/usr/local/lib/python3.6/site-packages/airflow/www/templates/admin/master.html", line 20, in top-level template code
    {% extends 'admin/base.html' %}
  File "/usr/local/lib/python3.6/site-packages/flask_admin/templates/bootstrap3/admin/base.html", line 38, in top-level template code
    {% block page_body %}
  File "/usr/local/lib/python3.6/site-packages/airflow/www/templates/admin/master.html", line 191, in block "page_body"
    {% block body %}
  File "/usr/local/lib/python3.6/site-packages/airflow/www/templates/airflow/dags.html", line 84, in block "body"
    <a href="{{ url_for('airflow.'+ dag.get_default_view(), dag_id=dag.dag_id) }}" title="{{ dag.description[0:80] + '...' if dag.description|length > 80 else dag.description }}">
TypeError: object of type 'NoneType' has no len()

What you expected to happen:

See UI

How to reproduce it:
Upgrade airflow
airflow upgradedb

[kaxil]

Duplicate of #8752

Will be fixed in 1.10.11