[Buildbot] #2959: Support a single config across the cluster, or something like that (was: Old Builders not defined anymore in the config are still there)

[Buildbot trac]

#2959: Support a single config across the cluster, or something like that
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Reporter:  Ben          |       Owner:
    Type:  defect       |      Status:  new
Priority:  major        |   Milestone:  0.9.+
 Version:  master       |  Resolution:
Keywords:  multimaster  |
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Ticket URL: <http://trac.buildbot.net/ticket/2959#comment:12>
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