There are a few fixes which are marked for 0.8 and "fixed" in JIRA but have only been pushed to trunk and missing from 0.8
https://issues.apache.org/jira/browse/KAFKA-985 (also affectsVersion is 0.9 and fixVersion is 0.8.1)
Were this mislabeled in JIRA or should they be present on the 0.8 branch.
At the same time there seem to be issues on the 0.8 branch which are absent from trunk (e.g. KAFKA-989).