no default for from_cluster.

[petersilva]

Some users seeing errors:

2019-10-03 16:05:45,830 [ERROR] message without a cluster amqp header['from_cluster']
2019-10-03 16:05:45,864 [ERROR] message without a cluster amqp header['from_cluster']
2019-10-03 16:05:45,897 [ERROR] message without a cluster amqp header['from_cluster']
2019-10-03 16:05:45,932 [ERROR] message without a cluster amqp header['from_cluster']
2019-10-03 16:05:45,964 [ERROR] message without a cluster amqp header['from_cluster']

This is caused by this patch 46a9654
which is inexplicable... it was likely temporary work done on a branch for experimental reasons and should never have been merged.