Backport of fixes from more recent branches:

Fixed incorrect millisecond to second conversion for retry_backoff_ms #216
Fixed unnecessary sleep after exhausted retries #166
Changed Kafka send errors to log as warn #179

.travis.yml

@@ -7,7 +7,9 @@ rvm:
   - jruby-1.7.25
 env:
   - KAFKA_VERSION=0.10.0.1
-before_install: ./kafka_test_setup.sh
+before_install:
+  - gem install bundler -v '< 2'
+  - ./kafka_test_setup.sh
 before_script:
   - bundle exec rake vendor
 script: bundle exec rspec && bundle exec rspec --tag integration

CHANGELOG.md

@@ -1,3 +1,9 @@
+## 5.1.12
+  - Backport of fixes from more recent branches:
+    - Fixed incorrect millisecond to second conversion for retry_backoff_ms [#216](https://github.com/logstash-plugins/logstash-output-kafka/pull/216)
+    - Fixed unnecessary sleep after exhausted retries [#166](https://github.com/logstash-plugins/logstash-output-kafka/pull/166)
+    - Changed Kafka send errors to log as warn [#179](https://github.com/logstash-plugins/logstash-output-kafka/pull/179)
+
 ## 5.1.11
   - Bugfix: Sends are now retried until successful. Previously, failed transmissions to Kafka 
     could have been lost by the KafkaProducer library. Now we verify transmission explicitly.