[Buildbot] #3569: fail when buildbot upgrade-master is run from a <=0.8.x installation

[Buildbot trac]

#3569: fail when buildbot upgrade-master is run from a <=0.8.x installation
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Reporter:  tardyp  |      Owner:
    Type:  task    |     Status:  new
Priority:  major   |  Milestone:  0.9.0
 Version:  master  |   Keywords:
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 {{{
 <djmitche> I think we intend 'buildbot upgrade-master' to work
 18:57:26 D<@djmitche> just at the cost of a lot of data loss
 18:57:30 T<@tomprince> I think we should drop all the code to support
 upgrading, since we don't preserve any of the interesting data.
 18:57:32 D<@djmitche> so those tests are testing intended functionality
 18:57:46 D<@djmitche> scheduler state, change-source state, etc. are
 preserved
 18:57:50 D<@djmitche> there's some value there
 18:57:56 T<@tardyp> that is a good thing to do indeed.
 18:57:56 T<@tomprince> Some of the code is to test loading changes from
 pickles.
 18:58:04 T<@tardyp> we can just fail if the db is too old
 18:58:11 T<@tardyp> its easy
 18:58:16 T<@tardyp> and we remove those old tests
 18:58:50 T<@tomprince> Do we care about upgrading from anything
 pre-0.8.12?
 18:59:03 T<@tardyp> I think it makes sense, and will prevent mistakingly
 update with pip install -U buildbot
 18:59:13 D<@djmitche> that's a good point
 }}}

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Ticket URL: <http://trac.buildbot.net/ticket/3569>
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