issues: 1052851176

I had to cancel the 0.59.2 release because ReadTheDocs was failing to build the documentation.

https://readthedocs.org/projects/datasette/builds/15268454/

``` /home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/bin/python -m sphinx -T -b html -d _build/doctrees -D language=en . _build/html Running Sphinx v1.8.5 loading translations [en]... done making output directory... building [mo]: targets for 0 po files that are out of date building [html]: targets for 27 source files that are out of date updating environment: 27 added, 0 changed, 0 removed reading sources... [ 3%] authentication

Traceback (most recent call last): File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/cmd/build.py", line 304, in build_main app.build(args.force_all, filenames) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/application.py", line 341, in build self.builder.build_update() File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/builders/init.py", line 347, in build_update len(to_build)) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/builders/init.py", line 360, in build updated_docnames = set(self.read()) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/builders/init.py", line 468, in read self._read_serial(docnames) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/builders/init.py", line 490, in _read_serial self.read_doc(docname) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/builders/init.py", line 534, in read_doc doctree = read_doc(self.app, self.env, self.env.doc2path(docname)) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/io.py", line 318, in read_doc pub.publish() File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/docutils/core.py", line 219, in publish self.apply_transforms() File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/docutils/core.py", line 200, in apply_transforms self.document.transformer.apply_transforms() File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/transforms/init.py", line 90, in apply_transforms Transformer.apply_transforms(self) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/docutils/transforms/init.py", line 171, in apply_transforms transform.apply(**kwargs) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/transforms/init.py", line 245, in apply apply_source_workaround(n) File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/util/nodes.py", line 94, in apply_source_workaround for classifier in reversed(node.parent.traverse(nodes.classifier)): TypeError: argument to reversed() must be a sequence

Exception occurred: File "/home/docs/checkouts/readthedocs.org/user_builds/datasette/envs/0.59.2/lib/python2.7/site-packages/sphinx/util/nodes.py", line 94, in apply_source_workaround for classifier in reversed(node.parent.traverse(nodes.classifier)): TypeError: argument to reversed() must be a sequence The full traceback has been saved in /tmp/sphinx-err-vkl0oE.log, if you want to report the issue to the developers. Please also report this if it was a user error, so that a better error message can be provided next time. A bug report can be filed in the tracker at https://github.com/sphinx-doc/sphinx/issues. Thanks! ```