Do not return Jedis conns to pool after NPE

DATAREDIS-153

- Return conn to pool as broken resource if NPE
occurs (for example if a null key or value is given),
preventing later flush of OutputStream with incomplete
data

- Workaround Jedis issue in pub/sub tests that prevents
subscribing with a pooled connection

- Continue not using pool in conn tests, as they
are too brittle with potentially unclosed pipelines,
unexecuted txs, etc

src/main/java/org/springframework/data/redis/connection/jedis/JedisConnection.java

@@ -162,6 +162,10 @@ public class JedisConnection implements RedisConnection {
 	}
 
 	protected DataAccessException convertJedisAccessException(Exception ex) {
+		if(ex instanceof NullPointerException) {
+			// An NPE before flush will leave data in the OutputStream of a pooled connection
+			broken = true;
+		}
 		DataAccessException exception = JedisConverters.toDataAccessException(ex);
 		if (exception instanceof RedisConnectionFailureException) {
 			broken = true;