It looks like even though the fix for this¹ was backported to the 1.1 line² as part of the PR³, the ticket didn't get updated to include a fix version of 1.1.1, and thus missed inclusion in the 1.1.1 release notes.
1 - https://issues.apache.org/jira/browse/KAFKA-6929 2 - https://github.com/apache/kafka/commit/a346590895f1702799d2c165c1a301de90a1d649 3 - https://github.com/apache/kafka/pull/5060 - Jordan Pilat
