This is still happening, and I reported the same to mediawiki-l-owner and @Platonides was kind to respond to better open a phabricator issue for this. But it's already open ;-)

OK, understood. Thanks for clearing that up! 👍

While I understand that there's no SQL query executed here, is it really harmless to have Mediawiki echo everything back that is passed in the URL? In a Mediawiki 1.34.0 installation I get:

IMHO adding /bin/bash to open_basedir should not be recommended. This directive is often used to explicitly limit file system access for PHP. Allowing PHP to call a system shell doesn't sound like a good idea to me. (MW 1.26 here, the warning is logged 3 times for each picture upload, but no UI errors - only includes/limit.sh is never called, of course.)