[Buildbot] #3308: make ChangeManager from master/buildbot/changes/manager.py inherit from MeasuredBuildbotServiceManager

[Buildbot trac]

#3308: make ChangeManager from master/buildbot/changes/manager.py inherit from
MeasuredBuildbotServiceManager
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Reporter:  yetanotherion  |      Owner:  yetanotherion
    Type:  enhancement    |     Status:  new
Priority:  major          |  Milestone:  0.9.+
 Version:  master         |   Keywords:  refactor
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 The code looks similar enough to deserve some factorization

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Ticket URL: <http://trac.buildbot.net/ticket/3308>
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Buildbot: build/test automation