[Buildbot] #3322: buildbot nine install automatically with pip < 1.4

[Buildbot trac]

#3322: buildbot nine install automatically with pip < 1.4
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Reporter:  tardyp  |      Owner:
    Type:  defect  |     Status:  new
Priority:  major   |  Milestone:  0.9.0
 Version:  master  |   Keywords:
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 pip 1.4 introduces the --pre option.


 before that, pip install -U buildbot will upgrade buildbot to nine
 version.
 This has been a problem for some users who have upgraded their database to
 nine, and couldn't go back.

 We should make a guardian in setup.py to refuse to install if pip > 1.4 is
 not present.

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Ticket URL: <http://trac.buildbot.net/ticket/3322>
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Buildbot: build/test automation