I was testing out https://www.mediawiki.org/wiki/Special:VisualEditorSandbox and Google Chrome is throwing a warning:
The page at https://www.mediawiki.org/wiki/Special:VisualEditorSandbox displayed insecure content from http://upload.wikimedia.org/wikipedia/commons/4/42/Loading.gif.
I assume this is simply hard-coded somewhere? I haven't had a chance to look at the code very closely, but this should be a simple fix.
Version: 1.18.x
Severity: blocker