Nullpointer using 'old' producer with 0.9.0 when node fails

[Gerard Klijs <ge...@dizzit.com>]

I don't think it's a big problem, but I just ran into an issue playing
around with vagrant. I was using the 0.9.0 github branch to run kafka, and
used vagrant to (by default) bring up one zookeeper and 3 broker instances.
Then I created two topics like:

./bin/kafka-topics.sh --create --zookeeper 192.168.50.1:2181
--replication-factor 3 --partitions 1 --topic transactions

After this I ran a demo project, build with the 0.8.2.1 sources. All worked
well. But when bringing down a broker, I got a nullpointer,
because org.apache.kafka.common.PartitionInfo no longer had a leader
object. causing a nullpointer at line 75. This nullpointer is already
resolved by revision 0699ff2ce60abb466cab5315977a224f1a70a4da introducing
the new consumer. Also it's only affecting the producer. But it might by
nice to now this can happen for people looking to upgrade their server,
while using old clients.