[Buildbot] #3166: fix 'buildbot.net' build slave

[Buildbot trac]

#3166: fix 'buildbot.net' build slave
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Reporter:  sa2ajj  |       Owner:
    Type:  task    |      Status:  new
Priority:  major   |   Milestone:  sys - on-bb-infra
 Version:          |  Resolution:
Keywords:          |
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Comment (by dustin):

 It looks like builds and docs both have the same error, and it's from
 using a bashism, `source`, instead of the portable but inscrutible `.`.
 Making that substitution in the config should fix the issue.

 As for coverage, I think we can just delete that builder, since we have
 coveralls running now.

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Ticket URL: <http://trac.buildbot.net/ticket/3166#comment:1>
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