How to disable JIRA comments

The Gitlab 8.14 release announcement says this:

A more silent GitLab in JIRA
When you setup the JIRA service within GitLab, by default, every commit and merge request in GitLab that referenced a JIRA issue created a comment in this issue in JIRA. Some people like having the complete details of what’s going on, others prefer this to be more silent.

With GitLab 8.14, you can now disable the creation of comments when referencing a JIRA issue in a commit or in a merge request.

The problem is that i do not find any configuration parameter to disable JIRA comments. We are using Gitlab 8.14.0 cde955c .