[Buildbot] #3588: duplicated tags in builder config leads to db consistency error

[Buildbot trac]

#3588: duplicated tags in builder config leads to db consistency error
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Reporter:  tardyp  |      Owner:
    Type:  defect  |     Status:  new
Priority:  major   |  Milestone:  0.9.0
 Version:  master  |   Keywords:
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 tags shall be deduped at the configuration layer

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Ticket URL: <http://trac.buildbot.net/ticket/3588>
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Buildbot: build/test automation