We've changed the way that <pre> tags are handled on Moodle web pages to make them a lot more useful.
This should work on legacy assignment write-ups without any changes -- any of the inline span-tags that you were using to color the code before will be stripped out automatically.
By default, the injector assumes that the contents of any pre-tag are Java code. If you want to use a different language, add a
data-lang="..." attribute to your pre-tag, where the value of the attribute is the MIME type of the content (or "text/plain" for no highlighting). For example:
<pre data-lang="text/x-haskell"> type Bag a = [(a, Int)] </pre>
The appropriate MIME types for your favorite language can be found by clicking on that language from CodeMirror's main site.
E-mail me or Steve if you notice any problems with this new feature.