encounter ''NoneType' object is not iterable'

[jichenjc]

https://review.openstack.org/#/c/463446/3
had this issue, master branch didn't have issue while I did not change too much stuff in this patch, might be related to some recent sphinx changes ?

File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/sphinx/builders/init.py", li ne 440, in _write_serial
34 self.write_doc(docname, doctree)
35 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/sphinx/builders/html.py", line 5 56, in write_doc
36 self.handle_page(docname, ctx, event_arg=doctree)
37 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/sphinx/builders/html.py", line 9 40, in handle_page
38 output = self.templates.render(templatename, ctx)
39 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/sphinx/jinja2glue.py", line 176, in render
40 return self.environment.get_template(template).render(context)
41 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/jinja2/environment.py", line 100 8, in render
42 return self.environment.handle_exception(exc_info, True)
43 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/jinja2/environment.py", line 780 , in handle_exception
44 reraise(exc_type, exc_value, tb)
45 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/sphinx/themes/basic/page.html", line 10, in top-level template code
46 {%- extends "layout.html" %}
47 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/oslosphinx/theme/openstack/layou t.html", line 2, in top-level template code
48 {% set css_files = css_files + ['_static/tweaks.css'] %}
49 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/sphinx/themes/basic/../basic/lay out.html", line 128, in top-level template code
50 {%- block csss %}
51 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/sphinx/themes/basic/../basic/lay out.html", line 129, in block "csss"
52 {{ css() }}
53 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/jinja2/sandbox.py", line 427, in call
54 return __context.call(__obj, *args, **kwargs)
55 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/jinja2/runtime.py", line 553, in _invoke
56 rv = self._func(*arguments)
57 File "/home/jichen/stack-forge-nova-zvm/nova-zvm-virt-driver/.tox/docs/local/lib/python2.7/site-packages/sphinx/themes/basic/../basic/lay out.html", line 108, in template
58 {%- for css in css_files %}

[tk0miya]

Sorry for inconvenience.
That was already fixed at #3754.

[jichenjc]

thanks a lot for your help~