[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  |  Resolution:
Keywords:          |
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Comment (by tardyp):

 2) If I take an existing buildmaster, adjust the configuration so it has a
 many-to-many (builder, tag) relation, and then run "buildbot reconfig" I
 get a couple exceptions.  I do not know if the same thing happens if there
 is no pre-existing database.  In the old configuration that did not cause
 problems where no builder had more than one tag.  Some old tags went away
 entirely.

 This constriant violation happens every time buildbot reconfig or buildbot
 start runs.

 2016-07-29 14:33:01-0400 [-] Got fatal Exception on DB
         Traceback (most recent call last):
         Failure: sqlalchemy.exc.IntegrityError:
 (pysqlite2.dbapi2.IntegrityError) columns builderid, tagid are not unique
 [SQL: u'INSERT INTO builders_tags (builderid, tagid) VALUES (?, ?)']
 [parameters: ((172, 23), (172, 23))]

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Ticket URL: <http://trac.buildbot.net/ticket/3588#comment:1>
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