This while discovered testing MDL-72242, which testing instructions used filter_censor to verify some behaviors.

In that issue it was detected that the filter is behaving strangely, with the following details:

1. It simply doesn't work. Create any content with the HTML editor having the "qqqq" word (for example). Then enable the filter and add that word to the configuration. Refresh the content page and nothing happens.
2. Extremely fun result if using when the configured words include a word like "<qqqq", (containing < or > chars). In that case all the contents become completely broken showing a lot of "internal" stuff (strings like {{<%1%0%>}}..).
3. The filter lacks any unit test.

So, basically, unless I'm missing something, the filter is not working at all. Initially I thought that it maybe because of the order of the filters (I had a lot enabled) because I couldn't believe what I was getting. But have tried disabling all the filters (keeping only the censor one) and very same results.

Ciao