ZOOKEEPER-3061: add more details to 'Unhandled scenario for peer' log.warn message

Author: Christine Poerschke <cpoerschke@bloomberg.net>
Author: Christine Poerschke <cpoerschke@apache.org>

Reviewers: Allan Lyu <fangmin@apache.org>, Benjamin Reed <breed@apache.org>, Norbert Kalmar <nkalmar@yahoo.com>

Closes #555 from cpoerschke/master-ZOOKEEPER-3061 and squashes the following commits:

139968228 [Christine Poerschke] Merge remote-tracking branch 'origin/master' into master-ZOOKEEPER-3061
1840c2bb6 [Christine Poerschke] Merge remote-tracking branch 'origin/master' into master-ZOOKEEPER-3061
1d3e7bc0b [Christine Poerschke] ZOOKEEPER-3061: add more details to 'Unhandled scenario for peer' log.warn message

src/java/main/org/apache/zookeeper/server/quorum/LearnerHandler.java

@@ -792,7 +792,14 @@ public class LearnerHandler extends ZooKeeperThread {
                     txnProposalItr.close();
                 }
             } else {
-                LOG.warn("Unhandled scenario for peer sid: " +  getSid());
+                LOG.warn("Unhandled scenario for peer sid: {} maxCommittedLog=0x{}"
+                        + " minCommittedLog=0x{} lastProcessedZxid=0x{}"
+                        + " peerLastZxid=0x{} txnLogSyncEnabled={}", getSid(),
+                        Long.toHexString(maxCommittedLog),
+                        Long.toHexString(minCommittedLog),
+                        Long.toHexString(lastProcessedZxid),
+                        Long.toHexString(peerLastZxid),
+                        txnLogSyncEnabled);
             }
             LOG.debug("Start forwarding 0x" + Long.toHexString(currentZxid) +
                       " for peer sid: " +  getSid());