Make updateChange actually update the change
Make updateChange actually update the change

Several assignments in updateChange would actually just keep
appending data causing immensely large data structures (which
are later traversed putting Zuul into a significant busy loop).

Make sure that data are replaced instead of augmented.

Change-Id: I8c6528adbbe24d30f8d5bb8b55bb731fefd9941a

wikimedia/integration-zuul,devdattakulkarni/zuul_messaging,gooddata/zuul,gooddata/zuul,wikimedia/integration-zuul,gooddata/zuul,devdattakulkarni/zuul_messaging,gooddata/zuul,gooddata/zuul,devdattakulkarni/zuul_messaging,wikimedia/integration-zuul,wikimedia/integration-zuul