[Systems] Upgrading wiki.sugarlabs.org to MediaWiki 1.35

[Bernie Innocenti]

I upgraded https://wiki-devel.sugarlabs.org to the REL_1.35 branch ahead 
of upgrading the main wiki.

This time, the update went relatively smoothly (last time I had to skip 
ahead multiple releases containing major structural changes). Notes:

  - MW 1.35 is a LTS release. We could choose to stay on it, but we 
would still have to track the REL_1.35 branch to get security and 
stability updates. Then, we'd have a more painful update to the next LTS 
in 2 years. Personally, I'd prefer tracking the official releases every 
6 months, but it will be up to whoever volunteers to maintain the wiki.

  - The VisualEditor is now bundled with MW, and does not require 
Parsoid. However, it's not working on wiki-devel. Still haven't figured why.

  - I noticed from the logs that wiki-devel is being crawled by multiple 
web spiders. It uses bandwidth and cpu time, so we should disallow it. 
The main wiki could also use some narrowing rules for robots: 
https://www.mediawiki.org/wiki/Manual:Robots.txt

  - Finally, I noticed that join.sugarlabs.org breaks the MW parser. I 
figured that removing the Widgets extension fixes it, and then I also 
found the offending line:

  {{Iframe|See [http://planet.sugarlabs.org Planet Sugar Labs], our blog 
aggregator |http://planet.sugarlabs.org|900|600|1}}

So I just deleted that line. The Planet doesn't have any new articles 
since 1 year ago, anyway. Do we use IFrame anywhere else? Can we just 
disable the Widgets plugin?

Since we're limited on sysadmin resources, I think we should aim to make 
the wiki as maintainable as possible, which means using a configuration 
as close as possible to upstream, and as few exotic extensions as possible.

Please test and let me know if you find any problems. I'd like to 
upgrade the production instance later this weekend.

-- 
_ // Bernie Innocenti
\X/  https://codewiz.org/