docs: Upgrade recommonmark to 0.6.0, fixing issues.

- recommonmark: 0.5.0 -> 0.6.0
- Fixed build TypeError: sequence item 1: expected str instance, NoneType found
  caused by recommonmark/parser.py erroring on a newline character.
- Removed deprecated code in conf.py that was causing warning messages
- Updated conf.py according to instructions for Sphinx-1.4 or newer
https://github.com/readthedocs/recommonmark/blob/master/README.md#getting-started
https://www.sphinx-doc.org/en/master/usage/markdown.html

This commit is also relevant to PR #13232.

docs/conf.py

@@ -29,7 +29,9 @@ from typing import Any, Dict, List, Optional
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = []  # type: List[str]
+extensions = [
+    'recommonmark',
+]  # type: List[str]
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
@@ -292,17 +294,16 @@ texinfo_documents = [
 # If true, do not generate a @detailmenu in the "Top" node's menu.
 #texinfo_no_detailmenu = False
 
-from recommonmark.parser import CommonMarkParser
 from recommonmark.transform import AutoStructify
 
-source_parsers = {
-    '.md': CommonMarkParser,
+# The suffix(es) of source filenames. You can specify multiple suffix
+# as a dictionary mapping file extensions to file types
+# https://www.sphinx-doc.org/en/master/usage/markdown.html:
+source_suffix = {
+    '.rst': 'restructuredtext',
+    '.md': 'markdown',
 }
 
-# The suffix(es) of source filenames.
-# You can specify multiple suffix as a list of string:
-source_suffix = ['.rst', '.md']
-
 # Temporary workaround to supress warnings after upgrading to recommonmark==0.5.0
 # Otherwise, sphinx build complains about all the links ending in .html
 # See PR # for more details

docs/development/remote.md

@@ -81,8 +81,7 @@ This will start up the Zulip server on port 9991. You can then
 navigate to `http://<REMOTE_IP>:9991` and you should see something like
 this screenshot of the Zulip development environment:
 
-![Image of Zulip development
-environment](../images/zulip-dev.png)
+![Image of Zulip development environment](../images/zulip-dev.png)
 
 The `--interface=''` option makes the Zulip development environment
 accessible from any IP address (in contrast with the much more secure

requirements/dev.txt

@@ -143,7 +143,7 @@ pytz==2019.2
 pyyaml==5.1.2             # via cfn-lint, moto, yamole
 qrcode==6.1               # via django-two-factor-auth
 queuelib==1.5.0           # via scrapy
-recommonmark==0.5.0
+recommonmark==0.6.0
 redis==3.3.8
 regex==2019.8.19
 requests-oauthlib==1.2.0  # via python-twitter, social-auth-core

requirements/docs.in

@@ -12,4 +12,4 @@ sphinx
 sphinx-rtd-theme
 
 # Needed to build markdown docs
-recommonmark==0.5.*  # https://github.com/zulip/zulip/issues/11395
+recommonmark

requirements/docs.txt

@@ -22,7 +22,7 @@ packaging==19.2           # via sphinx
 pygments==2.4.2           # via sphinx
 pyparsing==2.4.2          # via packaging
 pytz==2019.2              # via babel
-recommonmark==0.5.0
+recommonmark==0.6.0
 requests==2.22.0          # via sphinx
 six==1.12.0               # via packaging
 snowballstemmer==1.9.1    # via sphinx

version.py

@@ -26,4 +26,4 @@ LATEST_RELEASE_ANNOUNCEMENT = "https://blog.zulip.org/2019/03/01/zulip-2-0-relea
 #   historical commits sharing the same major version, in which case a
 #   minor version bump suffices.
 
-PROVISION_VERSION = '56.2'
+PROVISION_VERSION = '57.0'