I don't use Anarki myself, but figuring this out is easy with git.
Your first step is to find out if this was working earlier in the current branch; that is, did this get broken by a later commit or was it simply never ported to Arc 3.1?
If your find an earlier commit on the branch where it was working, finding out which commit exactly broke is easy: write a small shell script that returns true or false depending on whether the feature is working, and then use git-bisect (http://www.kernel.org/pub/software/scm/git/docs/git-bisect.h...)
Once you've found the commit that broke the feature, you can either look at the change yourself and/or contact the author of the commit.
